Function own_departure 

async fn own_departure(
    services: &Services,
    room_id: &RoomId,
    user_id: &UserId,
) -> Option<PduEvent>

The user’s own departure in a left room’s state, when it holds one.

A ban counts, since the membership indexes file a banned user as left. Any other membership yields None, as a room this server left still holds the invite a later rescission withdrew. A failed read is logged and yields None too, so the client still learns of the departure. A kick or ban is sent by someone else, so fields private to the sender are removed unless the user sent it.