I'm afraid the response will be the same when you create an SR with Pega Support for your query. Please try working on this with the forever chat team and let us know your findings. That would help us evaluate on next action.
We use Forever to start Chat node which in turn starts XMPP server. XMPP process is not directly managed through Forever. When Chat process is stopped, it should in turn manage shutdown of XMPP server, but this is not happening.
We have scripted to kill XMPP process whenever Chat is shutdown