I think Matrix suffers from some issues with large communities, for instance Graphene OS has already had to abandon 2-3 of their main group chats due to same bug and last time I checked (2-3 months ago) there has even been talks of switching to Discord. That is, just in case, a community of some of the most diehard privacy nerds btw
I also run a lot of proprietary stuff like Discord or Instagram due to peer pressure but I let it slide and put my hopes on Android sandboxing the apps and GrapheneOS tweaks. In my opinion, making sure that proprietary app can’t reliably access your data and never giving it anything sensitive yourself is a decent risk model.
The only proprietary software I use and somewhat trust is Obdisian. Honestly, it’s just excellent and I can’t see myself moving away from it anytime soon.