Soulblighter Music is right, Stoat is good, although still somewhat rough in some regards in my opinion, it's still open source so it runs on community contributions and donations.
Some other good ones that are worth giving a try:
- Root: https://www.rootapp.com/
- Fluxer: https://fluxer.app/
An interesting but harder to set up alternative is SpaceBarChat: https://github.com/spacebarchat/spacebarchat
It's basically self-hosted Discord, so instead of having Discord host your servers on their infrastructure, you host them on your own machine and use the Discord client API interface to communicate with the server. This means using it exactly like Discord, with the bonus that there's no one to monitor your activity there since you're hosting the server on your own private machine. Self hosting also means you bypass age verification, telemetry and all of the privacy critical concerns.