diff --git a/changelog.d/18066.bugfix b/changelog.d/18066.bugfix
new file mode 100644
index 00000000000..c979822bf0b
--- /dev/null
+++ b/changelog.d/18066.bugfix
@@ -0,0 +1 @@
+Fixed a bug that caused new space-visible rooms to be hidden from the space hierarchy when any server modules are loaded.
\ No newline at end of file
diff --git a/synapse/handlers/event_auth.py b/synapse/handlers/event_auth.py
index c4dbf22408b..002eb4caf78 100644
--- a/synapse/handlers/event_auth.py
+++ b/synapse/handlers/event_auth.py
@@ -21,6 +21,8 @@
 import logging
 from typing import TYPE_CHECKING, List, Mapping, Optional, Union
 
+from immutabledict import immutabledict
+
 from synapse import event_auth
 from synapse.api.constants import (
     EventTypes,
@@ -326,13 +328,13 @@ async def get_rooms_that_allow_join(
 
         # If allowed is of the wrong form, then only allow invited users.
         allow_list = join_rules_event.content.get("allow", [])
-        if not isinstance(allow_list, list):
+        if not isinstance(allow_list, (list, tuple)):
             return ()
 
         # Pull out the other room IDs, invalid data gets filtered.
         result = []
         for allow in allow_list:
-            if not isinstance(allow, dict):
+            if not isinstance(allow, (dict, immutabledict)):
                 continue
 
             # If the type is unexpected, skip it.
diff --git a/synapse/handlers/room_summary.py b/synapse/handlers/room_summary.py
index 64f5bea014f..b2338727035 100644
--- a/synapse/handlers/room_summary.py
+++ b/synapse/handlers/room_summary.py
@@ -955,7 +955,7 @@ def as_json(self, for_client: bool = False) -> JsonDict:
 
 def _has_valid_via(e: EventBase) -> bool:
     via = e.content.get("via")
-    if not via or not isinstance(via, list):
+    if not via or not isinstance(via, (list, tuple)):
         return False
     for v in via:
         if not isinstance(v, str):