Probably the app is making that decision. @jb55 might clarify
Discussion
Can you perhaps check this and see if the answer is in this code?
https://github.com/damus-io/damus/blob/master/damus/Views/MainTabView.swift
Not there but you can see the remove_relay function here:
https://github.com/damus-io/damus/blob/master/damus/Nostr/RelayPool.swift