diff --git a/changelog.d/11693.misc b/changelog.d/11693.misc
new file mode 100644
index 000000000..521a1796b
--- /dev/null
+++ b/changelog.d/11693.misc
@@ -0,0 +1 @@
+Remove debug logging for #4422, which has been closed since Synapse 0.99.
\ No newline at end of file
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 7baf3f199..4b3f1ea05 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -60,10 +60,6 @@ if TYPE_CHECKING:
 
 logger = logging.getLogger(__name__)
 
-# Debug logger for https://github.com/matrix-org/synapse/issues/4422
-issue4422_logger = logging.getLogger("synapse.handler.sync.4422_debug")
-
-
 # Counts the number of times we returned a non-empty sync. `type` is one of
 # "initial_sync", "full_state_sync" or "incremental_sync", `lazy_loaded` is
 # "true" or "false" depending on if the request asked for lazy loaded members or
@@ -1161,13 +1157,8 @@ class SyncHandler:
 
         num_events = 0
 
-        # debug for https://github.com/matrix-org/synapse/issues/4422
+        # debug for https://github.com/matrix-org/synapse/issues/9424
         for joined_room in sync_result_builder.joined:
-            room_id = joined_room.room_id
-            if room_id in newly_joined_rooms:
-                issue4422_logger.debug(
-                    "Sync result for newly joined room %s: %r", room_id, joined_room
-                )
             num_events += len(joined_room.timeline.events)
 
         log_kv(
@@ -1740,18 +1731,6 @@ class SyncHandler:
                         old_mem_ev_id, allow_none=True
                     )
 
-                # debug for #4422
-                if has_join:
-                    prev_membership = None
-                    if old_mem_ev:
-                        prev_membership = old_mem_ev.membership
-                    issue4422_logger.debug(
-                        "Previous membership for room %s with join: %s (event %s)",
-                        room_id,
-                        prev_membership,
-                        old_mem_ev_id,
-                    )
-
                 if not old_mem_ev or old_mem_ev.membership != Membership.JOIN:
                     newly_joined_rooms.append(room_id)
 
@@ -1893,13 +1872,6 @@ class SyncHandler:
                     upto_token=since_token,
                 )
 
-            if newly_joined:
-                # debugging for https://github.com/matrix-org/synapse/issues/4422
-                issue4422_logger.debug(
-                    "RoomSyncResultBuilder events for newly joined room %s: %r",
-                    room_id,
-                    entry.events,
-                )
             room_entries.append(entry)
 
         return _RoomChanges(
@@ -2077,14 +2049,6 @@ class SyncHandler:
             # `_load_filtered_recents` can't find any events the user should see
             # (e.g. due to having ignored the sender of the last 50 events).
 
-            if newly_joined:
-                # debug for https://github.com/matrix-org/synapse/issues/4422
-                issue4422_logger.debug(
-                    "Timeline events after filtering in newly-joined room %s: %r",
-                    room_id,
-                    batch,
-                )
-
             # When we join the room (or the client requests full_state), we should
             # send down any existing tags. Usually the user won't have tags in a
             # newly joined room, unless either a) they've joined before or b) the