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.

I stared at that logo trying to work out what it said for a bit... When I finally noticed that the domain in the link was what it said... I realised just how unreadable that logo is....