If it is from Meta assume it’s compromised.

I got it from F-Droid for free.

Concersations.im. It’s my backup because it supports OMEMO and OpenPGP.

Besides that, Element (Matrix). I use it for its public rooms.

I’m using CalyxOS and it’s pre-installed as a system app, so this seems like something that’s being built in at the AOSP level of development.