I am guilty of being one of the few persons to have left an open lobby for >20 minutes by mistake. I think it’s a bug to not timeout lobbies after inactivity of about 10 minutes from host.
Sometimes emergencies happen and you completely forget you have a lobby open. I have seen 1 lobby open for more than 25 hours , where people just kept running into only to find much later host is not there.
Voobly has such a feature. Makes life much more easy and to be honest, your servers might be a little more efficient in terms of resource usage by timing out afk lobbies.
Idk how you intend to do that though. Mouse movement listeners or a heartbeat to system asking for activity instance on the PC seams the way to go. Idk if you consider this a major problem but in my opinion, this does seem really annoying.