Guest users are allowed room initialSync

api/client-server/v1/rooms.yaml

@@ -371,7 +371,7 @@ paths:
                 description: |-
                   Whether this room is visible to the ``/publicRooms`` API
                   or not."
-            required: ["room_id", "membership"]
+            required: ["room_id"]
         403:
           description: >
             You aren't a member of the room and weren't previously a

specification/modules/guest_access.rst

@@ -32,6 +32,7 @@ retrieving events:
 * `GET /rooms/:room_id/state <#get-matrix-client-api-v1-rooms-roomid-state>`_
 * `GET /rooms/:room_id/state/:event_type/:state_key <#get-matrix-client-api-v1-rooms-roomid-state-eventtype-statekey>`_
 * `GET /rooms/:room_id/messages <#get-matrix-client-api-v1-rooms-roomid-messages>`_
+* `GET /rooms/:room_id/initialSync <#get-matrix-client-api-v1-rooms-roomid-initialsync>`_
 
 There is also a special version of the
 `GET /events <#get-matrix-client-api-v1-events>`_ endpoint: