diff --git a/changelog.d/12395.misc b/changelog.d/12395.misc
new file mode 100644
index 000000000000..0a2123b2942a
--- /dev/null
+++ b/changelog.d/12395.misc
@@ -0,0 +1 @@
+Remove an unstable identifier from [MSC3083](https://github.com/matrix-org/matrix-doc/pull/3083).
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 69d833585f2a..e67af6463fc7 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -687,8 +687,6 @@ async def on_send_join_request(
         time_now = self._clock.time_msec()
         event_json = event.get_pdu_json(time_now)
         resp = {
-            # TODO Remove the unstable prefix when servers have updated.
-            "org.matrix.msc3083.v2.event": event_json,
             "event": event_json,
             "state": [p.get_pdu_json(time_now) for p in state_events],
             "auth_chain": [p.get_pdu_json(time_now) for p in auth_chain_events],
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index d4b3cb3e98ca..3a2d91c1065b 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -1379,16 +1379,6 @@ def __init__(self, room_version: RoomVersion, v1_api: bool):
                 prefix + "auth_chain.item",
                 use_float=True,
             ),
-            # TODO Remove the unstable prefix when servers have updated.
-            #
-            # By re-using the same event dictionary this will cause the parsing of
-            # org.matrix.msc3083.v2.event and event to stomp over each other.
-            # Generally this should be fine.
-            ijson.kvitems_coro(
-                _event_parser(self._response.event_dict),
-                prefix + "org.matrix.msc3083.v2.event",
-                use_float=True,
-            ),
             ijson.kvitems_coro(
                 _event_parser(self._response.event_dict),
                 prefix + "event",