Function get_delayed_event_route 

pub(crate) async fn get_delayed_event_route(
    __arg0: State<State>,
    body: Ruma<Request>,
) -> Result<Response>

GET /_matrix/client/unstable/org.matrix.msc4140/delayed_events/{delayId}

Returns one of the sender’s delayed events (MSC4140).

A finalised event carries its outcome and is kept for about a week; one no longer kept answers 404 like an unknown delay_id.