The connection excluded from this broadcast, by ID.

RoomBroadcastOptions.except names a live connection object, which has no meaning in another process — but connection IDs come from runtime.uuid() and are therefore globally unique, so carrying the ID is what lets the exclusion survive the wire. A receiving replica skips the member whose id matches; ordinarily none does, since the excluded peer is connected to the originating replica.

Absent for SSE channels, whose publish has no exclusion option.