From spec: [Changed in v1.16] The m.room.create event is now required in the following places: [invite_state](https://spec.matrix.org/v1.19/client-server-api/#get_matrixclientv3sync_response-200_invited-room) and [knock_state](https://spec.matrix.org/v1.19/client-server-api/#get_matrixclientv3sync_response-200_knocked-room) on [/sync](https://spec.matrix.org/v1.19/client-server-api/#get_matrixclientv3sync) responses. On [m.room.member](https://spec.matrix.org/v1.19/client-server-api/#mroommember) events, the invite_room_state and knock_room_state under unsigned on the event.
From spec:
[Changed in v1.16] The m.room.create event is now required in the following places:
invite_state and knock_state on /sync responses.
On m.room.member events, the invite_room_state and knock_room_state under unsigned on the event.