Update _on_new_receipts() to work with MSC2285 changes

changelog.d/12636.bugfix

@@ -0,0 +1 @@
+Update `_on_new_receipts()` to work with [MSC2285](https://github.com/matrix-org/matrix-spec-proposals/pull/2285) changes. This was missed in https://github.com/matrix-org/synapse/pull/12168.

synapse/replication/tcp/client.py

@@ -21,7 +21,7 @@
 from twisted.internet.protocol import ReconnectingClientFactory
 from twisted.python.failure import Failure
 
-from synapse.api.constants import EventTypes
+from synapse.api.constants import EventTypes, ReceiptTypes
 from synapse.federation import send_queue
 from synapse.federation.sender import FederationSender
 from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
@@ -402,7 +402,7 @@ async def _on_new_receipts(
  if not self._is_mine_id(receipt.user_id):
  continue
  if (
- receipt.data.get("hidden", False)
+ receipt.receipt_type == ReceiptTypes.READ_PRIVATE
  and self._hs.config.experimental.msc2285_enabled
  ):
  continue