If you don't need voice, there are a lot of options. Matrix has IRC support and encryption, and has voice options if you self host.

Riot is... A Discord clone without working voice and I found it to be an odd duck.

There's RocketChat.. More Slack like.

Mattermost.

I replaced my voice/video chats with Nextcloud Talk and/or Steam, based on the scenario. Outside of those, Matrix is good for community needs in my mind.