diff --git a/docs/testing/releases/651.md b/docs/testing/releases/651.md
new file mode 100644
index 00000000000..8768c688b15
--- /dev/null
+++ b/docs/testing/releases/651.md
@@ -0,0 +1,87 @@
+## Testing notes and ZIP for release 6.6.0
+
+Zip file for testing: [woocommerce-gutenberg-products-block.zip](https://github.com/woocommerce/woocommerce-gutenberg-products-block/files/7762015/woocommerce-gutenberg-products-block.zip)
+
+## Feature plugin and package inclusion in WooCommerce
+
+### Fix saving WooCommerce templates in WP 5.9 beta 3 ([5408](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5408))
+
+1. With WP 5.9 beta 3 and Gutenberg disabled, go to Appearance > Editor.
+2. Edit one of the WooCommerce templates and try to save it.
+3. Verify the template is saved without errors.
+4. Repeat the process with Gutenberg enabled and verify it works as well.
+
+### Fixed error reporting block templates do not exist after editing WooCommerce templates on WP 5.8. ([5425](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5425))
+
+Test the following under these scenarios:
+
+- WordPress 5.8 and the Gutenberg plugin
+- WordPress 5.9 and the Gutenberg plugin
+- WordPress 5.9 without the Gutenberg plugin
+
+1. Open the FSE editor
+2. From the sidebar on the left click on Templates.
+3. Click on one of these templates Product Category Page, Product Archive Page, Product Archive Page or Single Product Page.
+4. Edit the template and save it.
+5. Go back (not refresh the page, because you will reproduce a known bug (#5426).
+6. Reopen the same template and check if the changes are still there.
+7. Check if the template works correctly on the frontend side too.
+
+### Added By template column value is user friendly for modified WooCommerce block templates. ([5420](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5420))
+
+1. Modify one of the WooCommerce block templates via the Site Editor. Save it.
+2. Load the templates screen and ensure the Added By column value says WooCommerce and not woocommerce
+3. Ensure the modified version of the template loads in the Site Editor and on the frontend.
+
+### Avoid WooCommerce template names being editable. ([5385](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5385))
+
+1. With WC 6.0 beta 3 and a block theme installed, go to Appearance > Editor.
+2. Go to the Templates page and edit one of the WooCommerce templates (ie: Single Product Page).
+3. Save and refresh the page.
+4. Verify the template name is not editable.
+
+### Use the themes product archive block template for product category & product tag pages if the theme does not have more specific templates for those. ([5380](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5380))
+
+Add the following block markup to the following templates so you know which one is getting rendered:
+
+1. woo-blocks/archive-product.html
+2. woo-blocks/taxonomy-product_tag.html
+3. woo-blocks/taxonomy-product_cat.html
+
+Template:
+
+```
+<!-- wp:paragraph -->
+<p>Woo Blocks: [template-filename].html</p>
+<!-- /wp:paragraph -->
+```
+
+1. Install Gutenberg plugin and Blockbase theme to activate Site Editor and FSE.
+2. Go to a product category page and check that woo-blocks/taxonomy-product_cat.html is the template being used.
+3. Duplicate woo-blocks/archive-product.html into blockbase/block-templates/ and change the markup you added above to say "Blockbase" instead of "Woo Blocks" so we can differentiate.
+4. Reload the product category page, product tag page, and main shop page/product archive page and check that the archive-product.html from Blockbase is being loaded.
+5. Go into Site Editor > All Templates and check that "Product Archive Page", "Product Category Page" and "Product Tag Page" are all in the list and it states they're being loaded from the Blockbase theme
+6. Customise the Product Category Page template and save your changes
+7. Reload the product category page on the frontend and check the customised version of this template is being rendered.
+
+### Fixed issue with variable products add to cart error, and gallery not updating to show correct product variant image. ([5346](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5346))
+
+1. Install a Block Theme such as [TT1](https://en-gb.wordpress.org/themes/tt1-blocks/) and the [Gutenberg plugin](https://wordpress.org/plugins/gutenberg/).
+2. Load the product page of a variable product.
+3. Change some of the options (such as colour) on the variable product and check that the image in the product gallery updates to show the correct image for that variant.
+4. Clicking "Add to cart" should successfully add the product to the cart.
+
+### Fix error when reverting WooCommerce templates. ([5342](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5342))
+
+1. With WC 6.0 or later, Gutenberg and a block theme installed, go to Appearance > Editor.
+2. Go to the Templates page and edit one of the WooCommerce templates (ie: Single Product Page).
+3. In the frontend, verify the changes you just saved are applied.
+4. Go back to the Templates page and press on _Clear Customizations_ of the template you just edited.
+5. Verify there is no error and the changes have been reverted in the frontend.
+6. Repeat the steps above with WP 5.9 beta without Gutenberg enabled.
+
+### Fix: WooCommerce block templates loading for WP 5.9 without Gutenberg plugin. ([5335](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5335))
+
+1. Make sure you have WP 5.9 or above.
+2. Install a Block Theme such as [TT1](https://en-gb.wordpress.org/themes/tt1-blocks/).
+3. Make sure you can load the list of Block Templates in the Appearance > Site Editor
diff --git a/docs/testing/releases/README.md b/docs/testing/releases/README.md
index 4b5adde93d7..c7063f3195c 100644
--- a/docs/testing/releases/README.md
+++ b/docs/testing/releases/README.md
@@ -53,3 +53,4 @@ Every release includes specific testing instructions for new features and bug fi
     -   [6.3.3](./633.md)
 -   [6.4.0](./640.md)
 -   [6.5.0](./650.md)
+-   [6.5.1](./651.md)
diff --git a/package.json b/package.json
index a75583a4120..a4822deb23f 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
 	"name": "@woocommerce/block-library",
 	"title": "WooCommerce Blocks",
 	"author": "Automattic",
-	"version": "6.5.0",
+	"version": "6.5.1",
 	"description": "WooCommerce blocks for the Gutenberg editor.",
 	"homepage": "https://github.com/woocommerce/woocommerce-gutenberg-products-block/",
 	"keywords": [
diff --git a/readme.txt b/readme.txt
index b20271b9ba5..163d3434744 100644
--- a/readme.txt
+++ b/readme.txt
@@ -4,7 +4,7 @@ Tags: gutenberg, woocommerce, woo commerce, products, blocks, woocommerce blocks
 Requires at least: 5.8
 Tested up to: 5.8
 Requires PHP: 7.0
-Stable tag: 6.5.0
+Stable tag: 6.5.1
 License: GPLv3
 License URI: https://www.gnu.org/licenses/gpl-3.0.html
 
@@ -85,6 +85,18 @@ Release and roadmap notes available on the [WooCommerce Developers Blog](https:/
 
 == Changelog ==
 
+= 6.5.1 - 2021-12-22 =
+
+#### Bug Fixes
+
+- Fixed error reporting block templates do not exist after editing WooCommerce templates on WP 5.8. ([5425](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5425))
+- Added By template column value is user friendly for modified WooCommerce block templates. ([5420](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5420))
+- Avoid WooCommerce template names being editable. ([5385](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5385))
+- Use the themes product archive block template for product category & product tag pages if the theme does not have more specific templates for those. ([5380](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5380))
+- Fixed issue with variable products add to cart error, and gallery not updating to show correct product variant image. ([5346](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5346))
+- Fix error when reverting WooCommerce templates. ([5342](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5342))
+- Fix: WooCommerce block templates loading for WP 5.9 without Gutenberg plugin. ([5335](https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/5335))
+
 = 6.5.0 - 2021-12-06 =
 
 #### Enhancements
diff --git a/src/BlockTemplatesController.php b/src/BlockTemplatesController.php
index 6b4fc990b02..d5a9c0e4963 100644
--- a/src/BlockTemplatesController.php
+++ b/src/BlockTemplatesController.php
@@ -55,7 +55,7 @@ public function __construct() {
 	 */
 	protected function init() {
 		add_action( 'template_redirect', array( $this, 'render_block_template' ) );
-		add_filter( 'pre_get_block_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
+		add_filter( 'pre_get_block_file_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
 		add_filter( 'get_block_templates', array( $this, 'add_block_templates' ), 10, 3 );
 		add_filter( 'default_wp_template_part_areas', array( $this, 'add_template_part_areas' ) );
 		add_filter( 'wp_insert_post', array( $this, 'add_mini_cart_content_to_template_part' ), 10, 3 );
@@ -74,7 +74,13 @@ protected function init() {
 	 * @return mixed|\WP_Block_Template|\WP_Error
 	 */
 	public function maybe_return_blocks_template( $template, $id, $template_type ) {
-		if ( ! function_exists( 'gutenberg_get_block_template' ) ) {
+		// 'get_block_template' was introduced in WP 5.9. We need to support
+		// 'gutenberg_get_block_template' for previous versions of WP with
+		// Gutenberg enabled.
+		if (
+			! function_exists( 'gutenberg_get_block_template' ) &&
+			! function_exists( 'get_block_template' )
+		) {
 			return $template;
 		}
 		$template_name_parts = explode( '//', $id );
@@ -84,24 +90,29 @@ public function maybe_return_blocks_template( $template, $id, $template_type ) {
 		list( , $slug ) = $template_name_parts;
 
 		// Remove the filter at this point because if we don't then this function will infinite loop.
-		remove_filter( 'pre_get_block_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
+		remove_filter( 'pre_get_block_file_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
 
 		// Check if the theme has a saved version of this template before falling back to the woo one. Please note how
 		// the slug has not been modified at this point, we're still using the default one passed to this hook.
-		$maybe_template = gutenberg_get_block_template( $id, $template_type );
+		$maybe_template = function_exists( 'gutenberg_get_block_template' ) ?
+			gutenberg_get_block_template( $id, $template_type ) :
+			get_block_template( $id, $template_type );
+
 		if ( null !== $maybe_template ) {
-			add_filter( 'pre_get_block_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
+			add_filter( 'pre_get_block_file_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
 			return $maybe_template;
 		}
 
 		// Theme-based template didn't exist, try switching the theme to woocommerce and try again. This function has
 		// been unhooked so won't run again.
-		add_filter( 'get_block_template', array( $this, 'get_single_block_template' ), 10, 3 );
-		$maybe_template = gutenberg_get_block_template( 'woocommerce//' . $slug, $template_type );
+		add_filter( 'get_block_file_template', array( $this, 'get_single_block_template' ), 10, 3 );
+		$maybe_template = function_exists( 'gutenberg_get_block_template' ) ?
+			gutenberg_get_block_template( 'woocommerce//' . $slug, $template_type ) :
+			get_block_template( 'woocommerce//' . $slug, $template_type );
 
 		// Re-hook this function, it was only unhooked to stop recursion.
-		add_filter( 'pre_get_block_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
-		remove_filter( 'get_block_template', array( $this, 'get_single_block_template' ), 10, 3 );
+		add_filter( 'pre_get_block_file_template', array( $this, 'maybe_return_blocks_template' ), 10, 3 );
+		remove_filter( 'get_block_file_template', array( $this, 'get_single_block_template' ), 10, 3 );
 		if ( null !== $maybe_template ) {
 			return $maybe_template;
 		}
@@ -155,7 +166,7 @@ public function get_single_block_template( $template, $id, $template_type ) {
 	 * @return array
 	 */
 	public function add_block_templates( $query_result, $query, $template_type ) {
-		if ( ! function_exists( 'gutenberg_supports_block_templates' ) || ! gutenberg_supports_block_templates() ) {
+		if ( ! BlockTemplateUtils::supports_block_templates() ) {
 			return $query_result;
 		}
 
@@ -338,21 +349,25 @@ function ( $template ) use ( $template_slug ) {
 				continue;
 			}
 
+			// If the theme has an archive-product.html template, but not a taxonomy-product_cat.html template let's use the themes archive-product.html template.
+			if ( 'taxonomy-product_cat' === $template_slug && ! BlockTemplateUtils::theme_has_template( 'taxonomy-product_cat' ) && BlockTemplateUtils::theme_has_template( 'archive-product' ) ) {
+				$template_file = get_stylesheet_directory() . '/' . self::TEMPLATES_DIR_NAME . '/archive-product.html';
+				$templates[]   = BlockTemplateUtils::create_new_block_template_object( $template_file, $template_type, $template_slug, true );
+				continue;
+			}
+
+			// If the theme has an archive-product.html template, but not a taxonomy-product_tag.html template let's use the themes archive-product.html template.
+			if ( 'taxonomy-product_tag' === $template_slug && ! BlockTemplateUtils::theme_has_template( 'taxonomy-product_tag' ) && BlockTemplateUtils::theme_has_template( 'archive-product' ) ) {
+				$template_file = get_stylesheet_directory() . '/' . self::TEMPLATES_DIR_NAME . '/archive-product.html';
+				$templates[]   = BlockTemplateUtils::create_new_block_template_object( $template_file, $template_type, $template_slug, true );
+				continue;
+			}
+
 			// At this point the template only exists in the Blocks filesystem and has not been saved in the DB,
 			// or superseded by the theme.
-			$new_template_item = array(
-				'slug'        => $template_slug,
-				'id'          => 'woocommerce//' . $template_slug,
-				'path'        => $template_file,
-				'type'        => $template_type,
-				'theme'       => 'woocommerce',
-				'source'      => 'plugin',
-				'title'       => BlockTemplateUtils::convert_slug_to_title( $template_slug ),
-				'description' => '',
-				'post_types'  => array(), // Don't appear in any Edit Post template selector dropdown.
-			);
-			$templates[]       = (object) $new_template_item;
+			$templates[] = BlockTemplateUtils::create_new_block_template_object( $template_file, $template_type, $template_slug );
 		}
+
 		return $templates;
 	}
 
@@ -370,7 +385,6 @@ public function get_block_templates( $slugs = array(), $template_type = 'wp_temp
 		return array_merge( $templates_from_db, $templates_from_woo );
 	}
 
-
 	/**
 	 * Gets the directory where templates of a specific template type can be found.
 	 *
@@ -408,7 +422,7 @@ public function block_template_is_available( $template_name, $template_type = 'w
 	 * Renders the default block template from Woo Blocks if no theme templates exist.
 	 */
 	public function render_block_template() {
-		if ( is_embed() || ! function_exists( 'gutenberg_supports_block_templates' ) || ! gutenberg_supports_block_templates() ) {
+		if ( is_embed() || ! BlockTemplateUtils::supports_block_templates() ) {
 			return;
 		}
 
diff --git a/src/BlockTypes/LegacyTemplate.php b/src/BlockTypes/LegacyTemplate.php
index ae3d0efa309..4742ad8219a 100644
--- a/src/BlockTypes/LegacyTemplate.php
+++ b/src/BlockTypes/LegacyTemplate.php
@@ -34,6 +34,14 @@ protected function render( $attributes, $content ) {
 			return;
 		}
 
+		// We need to load the scripts here because when using block templates wp_head() gets run after the block template.
+		// As a result we are trying to enqueue required scripts before we have even registered them.
+		// See here for more information: https://github.com/woocommerce/woocommerce-gutenberg-products-block/issues/5328#issuecomment-989013447.
+		if ( class_exists( 'WC_Frontend_Scripts' ) ) {
+			$frontend_scripts = new \WC_Frontend_Scripts();
+			$frontend_scripts::load_scripts();
+		}
+
 		$archive_templates = array( 'archive-product', 'taxonomy-product_cat', 'taxonomy-product_tag' );
 
 		if ( 'single-product' === $attributes['template'] ) {
diff --git a/src/Package.php b/src/Package.php
index 8c0baed1b93..3dda2341801 100644
--- a/src/Package.php
+++ b/src/Package.php
@@ -106,7 +106,7 @@ public static function container( $reset = false ) {
 				NewPackage::class,
 				function ( $container ) {
 					// leave for automated version bumping.
-					$version = '6.5.0';
+					$version = '6.5.1';
 					return new NewPackage(
 						$version,
 						dirname( __DIR__ ),
diff --git a/src/Utils/BlockTemplateUtils.php b/src/Utils/BlockTemplateUtils.php
index 6e592a98269..13de440cf87 100644
--- a/src/Utils/BlockTemplateUtils.php
+++ b/src/Utils/BlockTemplateUtils.php
@@ -98,7 +98,7 @@ public static function gutenberg_build_template_result_from_post( $post ) {
 		$template                 = new \WP_Block_Template();
 		$template->wp_id          = $post->ID;
 		$template->id             = $theme . '//' . $post->post_name;
-		$template->theme          = $theme;
+		$template->theme          = 'woocommerce' === $theme ? 'WooCommerce' : $theme;
 		$template->content        = $post->post_content;
 		$template->slug           = $post->post_name;
 		$template->source         = 'custom';
@@ -107,8 +107,9 @@ public static function gutenberg_build_template_result_from_post( $post ) {
 		$template->title          = $post->post_title;
 		$template->status         = $post->post_status;
 		$template->has_theme_file = $has_theme_file;
-		$template->is_custom      = true;
+		$template->is_custom      = false;
 		$template->post_types     = array(); // Don't appear in any Edit Post template selector dropdown.
+
 		if ( 'wp_template_part' === $post->post_type ) {
 			$type_terms = get_the_terms( $post, 'wp_template_part_area' );
 			if ( ! is_wp_error( $type_terms ) && false !== $type_terms ) {
@@ -129,19 +130,26 @@ public static function gutenberg_build_template_result_from_post( $post ) {
 	 */
 	public static function gutenberg_build_template_result_from_file( $template_file, $template_type ) {
 		$template_file = (object) $template_file;
+
+		// If the theme has an archive-products.html template but does not have product taxonomy templates
+		// then we will load in the archive-product.html template from the theme to use for product taxonomies on the frontend.
+		$template_is_from_theme = 'theme' === $template_file->source;
+		$theme_name             = wp_get_theme()->get( 'TextDomain' );
+
 		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
-		$template_content         = file_get_contents( $template_file->path );
-		$template                 = new \WP_Block_Template();
-		$template->id             = 'woocommerce//' . $template_file->slug;
-		$template->theme          = 'WooCommerce';
-		$template->content        = self::gutenberg_inject_theme_attribute_in_content( $template_content );
-		$template->source         = 'plugin';
+		$template_content  = file_get_contents( $template_file->path );
+		$template          = new \WP_Block_Template();
+		$template->id      = $template_is_from_theme ? $theme_name . '//' . $template_file->slug : 'woocommerce//' . $template_file->slug;
+		$template->theme   = $template_is_from_theme ? $theme_name : 'WooCommerce';
+		$template->content = self::gutenberg_inject_theme_attribute_in_content( $template_content );
+		// Plugin was agreed as a valid source value despite existing inline docs at the time of creating: https://github.com/WordPress/gutenberg/issues/36597#issuecomment-976232909.
+		$template->source         = $template_file->source ? $template_file->source : 'plugin';
 		$template->slug           = $template_file->slug;
 		$template->type           = $template_type;
 		$template->title          = ! empty( $template_file->title ) ? $template_file->title : self::convert_slug_to_title( $template_file->slug );
 		$template->status         = 'publish';
 		$template->has_theme_file = true;
-		$template->origin         = 'plugin';
+		$template->origin         = $template_file->source;
 		$template->is_custom      = false; // Templates loaded from the filesystem aren't custom, ones that have been edited and loaded from the DB are.
 		$template->post_types     = array(); // Don't appear in any Edit Post template selector dropdown.
 		if ( 'wp_template_part' === $template_type ) {
@@ -154,6 +162,35 @@ public static function gutenberg_build_template_result_from_file( $template_file
 		return $template;
 	}
 
+	/**
+	 * Build a new template object so that we can make Woo Blocks default templates available in the current theme should they not have any.
+	 *
+	 * @param string $template_file Block template file path.
+	 * @param string $template_type wp_template or wp_template_part.
+	 * @param string $template_slug Block template slug e.g. single-product.
+	 * @param bool   $template_is_from_theme If the block template file is being loaded from the current theme instead of Woo Blocks.
+	 *
+	 * @return object Block template object.
+	 */
+	public static function create_new_block_template_object( $template_file, $template_type, $template_slug, $template_is_from_theme = false ) {
+		$theme_name = wp_get_theme()->get( 'TextDomain' );
+
+		$new_template_item = array(
+			'slug'        => $template_slug,
+			'id'          => $template_is_from_theme ? $theme_name . '//' . $template_slug : 'woocommerce//' . $template_slug,
+			'path'        => $template_file,
+			'type'        => $template_type,
+			'theme'       => $template_is_from_theme ? $theme_name : 'woocommerce',
+			// Plugin was agreed as a valid source value despite existing inline docs at the time of creating: https://github.com/WordPress/gutenberg/issues/36597#issuecomment-976232909.
+			'source'      => $template_is_from_theme ? 'theme' : 'plugin',
+			'title'       => self::convert_slug_to_title( $template_slug ),
+			'description' => '',
+			'post_types'  => array(), // Don't appear in any Edit Post template selector dropdown.
+		);
+
+		return (object) $new_template_item;
+	}
+
 	/**
 	 * Finds all nested template part file paths in a theme's directory.
 	 *
@@ -230,4 +267,20 @@ public static function theme_has_template_part( $template_name ) {
 		return is_readable( get_template_directory() . '/block-template-parts/' . $template_name . '.html' ) ||
 			is_readable( get_stylesheet_directory() . '/block-template-parts/' . $template_name . '.html' );
 	}
+
+	/**
+	 * Checks to see if they are using a compatible version of WP, or if not they have a compatible version of the Gutenberg plugin installed.
+	 *
+	 * @return boolean
+	 */
+	public static function supports_block_templates() {
+		if (
+			( ! function_exists( 'wp_is_block_theme' ) || ! wp_is_block_theme() ) &&
+			( ! function_exists( 'gutenberg_supports_block_templates' ) || ! gutenberg_supports_block_templates() )
+		) {
+			return false;
+		}
+
+		return true;
+	}
 }
diff --git a/woocommerce-gutenberg-products-block.php b/woocommerce-gutenberg-products-block.php
index 2293312ea84..2c416ab2298 100644
--- a/woocommerce-gutenberg-products-block.php
+++ b/woocommerce-gutenberg-products-block.php
@@ -3,7 +3,7 @@
  * Plugin Name: WooCommerce Blocks
  * Plugin URI: https://github.com/woocommerce/woocommerce-gutenberg-products-block
  * Description: WooCommerce blocks for the Gutenberg editor.
- * Version: 6.5.0
+ * Version: 6.5.1
  * Author: Automattic
  * Author URI: https://woocommerce.com
  * Text Domain:  woo-gutenberg-products-block