Device additions/removals are tracked by GvcMixerControl, which doesn't change when unsetting the stream. So clearing the menu manually was a workaround, not a fix.
It's also worth noting that I failed to reproduce the original issue again, so it's possible that we were working around a pipewire bug that has since been fixed.
This reverts commit 1b62b7ea.
Fixes #6207 (closed)