Stoat (formerly known as Revolt) is a selfhostable, FOSS replacement for discord [Group chats and voice channels you can join any time].
Cool new name, however not as easy to use in other languages.
Voice chat is stil not officialy implemented.
Self-hosting there. Apparently nothing to do for you if you had already hosted before the name change.
The Android app has unfortunately disappeared (not been updated) on F-droid.
Edit: added short description for clarification
The UI of the ones I’ve tried (schildichat, fluffy, element) felt very unintuitive to me. Spaces were really awkward because it was a different paradigm.
I’m hoping that the familiarity of cinny will help with wider adoption.