Function departed_out_of_band 

async fn departed_out_of_band(
    services: &Services,
    room_id: &RoomId,
    sender_user: &UserId,
    since: u64,
) -> bool

Whether the room holds no departure event this sync can send.

An invite rescinded or rejected after this server left the room writes only the membership row. The state then holds no departure for the user, or an older one with no event after the client’s position to diff it against, and either way the rest of the room’s frozen state is not theirs to receive. A ban stays with the ordinary loader, which serves it whatever the row’s count says, and so does any departure when the read of the room’s last event fails, which is logged and proves nothing.