diff --git a/Classes/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandler.php b/Classes/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandler.php
index ee178e9beb..90580decf4 100644
--- a/Classes/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandler.php
+++ b/Classes/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandler.php
@@ -25,7 +25,7 @@
 use Doctrine\DBAL\Driver\Exception as DBALDriverException;
 use TYPO3\CMS\Core\Database\ConnectionPool;
 use TYPO3\CMS\Core\Database\Query\QueryBuilder;
-use TYPO3\CMS\Core\Database\QueryGenerator;
+use TYPO3\CMS\Core\Domain\Repository\PageRepository;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 
 /**
@@ -173,8 +173,12 @@ protected function getSubPageIds(int $pageId): array
         // here we retrieve only the subpages of this page because the permission clause is not evaluated
         // on the root node.
         $permissionClause = ' 1 ' . $this->getPagesRepository()->getBackendEnableFields();
-        $treePageIdList = (string)$this->getQueryGenerator()->getTreeList($pageId, 20, 0, $permissionClause);
-        $treePageIds = array_map('intval', explode(',', $treePageIdList));
+        $pageRepository = GeneralUtility::makeInstance(PageRepository::class);
+        $treePageIds = $pageRepository->getDescendantPageIdsRecursive(
+            $pageId,
+            20,
+            0
+        );
 
         // the first one can be ignored because this is the page itself
         array_shift($treePageIds);
@@ -302,14 +306,6 @@ protected function getUpdateSubPagesRecursiveTriggerConfiguration(): array
         return $this->updateSubPagesRecursiveTriggerConfiguration;
     }
 
-    /**
-     * @return QueryGenerator
-     */
-    protected function getQueryGenerator(): QueryGenerator
-    {
-        return GeneralUtility::makeInstance(QueryGenerator::class);
-    }
-
     /**
      * @return PagesRepository
      */
diff --git a/Tests/Unit/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandlerTest.php b/Tests/Unit/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandlerTest.php
index 3780b393dd..e0bbc08093 100644
--- a/Tests/Unit/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandlerTest.php
+++ b/Tests/Unit/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandlerTest.php
@@ -23,7 +23,7 @@
 use ApacheSolrForTypo3\Solr\System\TCA\TCAService;
 use ApacheSolrForTypo3\Solr\Tests\Unit\UnitTest;
 use PHPUnit\Framework\MockObject\MockObject;
-use TYPO3\CMS\Core\Database\QueryGenerator;
+use TYPO3\CMS\Core\Domain\Repository\PageRepository;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 
 /**
@@ -63,6 +63,11 @@ abstract class AbstractUpdateHandlerTest extends UnitTest
      */
     protected $queryGeneratorMock;
 
+    /**
+     * @var PageRepository|MockObject
+     */
+    protected PageRepository|MockObject $typo3PageRepositoryMock;
+
     /**
      * @var PagesRepository|MockObject
      */
@@ -82,9 +87,9 @@ protected function setUp(): void
             ->method('getSolrConfigurationFromPageId')
             ->willReturn($this->typoScriptConfigurationMock);
 
-        $this->queryGeneratorMock = $this->createMock(QueryGenerator::class);
+        $this->typo3PageRepositoryMock = $this->createMock(PageRepository::class);
 
-        GeneralUtility::addInstance(QueryGenerator::class, $this->queryGeneratorMock);
+        GeneralUtility::addInstance(PageRepository::class, $this->typo3PageRepositoryMock);
         parent::setUp();
     }
 
diff --git a/Tests/Unit/Domain/Index/Queue/UpdateHandler/DataUpdateHandlerTest.php b/Tests/Unit/Domain/Index/Queue/UpdateHandler/DataUpdateHandlerTest.php
index 0c19b33e19..92fb1791c5 100644
--- a/Tests/Unit/Domain/Index/Queue/UpdateHandler/DataUpdateHandlerTest.php
+++ b/Tests/Unit/Domain/Index/Queue/UpdateHandler/DataUpdateHandlerTest.php
@@ -378,10 +378,10 @@ public function handlePageUpdateTriggersRecursivePageProcessing(): void
 
         $GLOBALS['TCA']['pages'] = ['columns' => []];
 
-        $this->queryGeneratorMock
+        $this->typo3PageRepositoryMock
             ->expects(self::any())
-            ->method('getTreeList')
-            ->willReturn($dummyPageRecord['uid'] . ',100,200');
+            ->method('getDescendantPageIdsRecursive')
+            ->willReturn([$dummyPageRecord['uid'], 100, 200]);
 
         $this->pagesRepositoryMock
             ->expects(self::any())
diff --git a/Tests/Unit/Domain/Index/Queue/UpdateHandler/GarbageHandlerTest.php b/Tests/Unit/Domain/Index/Queue/UpdateHandler/GarbageHandlerTest.php
index 34e9e95edf..fdc6c784c9 100644
--- a/Tests/Unit/Domain/Index/Queue/UpdateHandler/GarbageHandlerTest.php
+++ b/Tests/Unit/Domain/Index/Queue/UpdateHandler/GarbageHandlerTest.php
@@ -191,10 +191,10 @@ public function performRecordGarbageCheckTriggersPageGarbageCollection(): void
             ->with('pages', $dummyPageRecord)
             ->willReturn($dummyPageRecord);
 
-        $this->queryGeneratorMock
+        $this->typo3PageRepositoryMock
             ->expects(self::any())
-            ->method('getTreeList')
-            ->willReturn($dummyPageRecord['uid'] . ',100,200');
+            ->method('getDescendantPageIdsRecursive')
+            ->willReturn([$dummyPageRecord['uid'], 100, 200]);
 
         $this->garbageHandler->performRecordGarbageCheck($dummyPageRecord['uid'], 'pages', ['hidden' => 1], true);
     }