@jc0b zulip is so bad for personal stuff, this is exactly what i mean
as somebody who's been working on ircv3 for like.... 6 years and 5 irc clients, i would obviously recommend irc
specifically irc is still pretty behind the times on big networks like oftc and libera (for good reason) but if you set up a private ircd like ergo on a tiny server and serve a webapp for people to log into (like obsidianIRC) you can have a pretty user-friendly, discord-like experience while being compatible with dozens of clients, bots and remaining future proof for basically ever.
if you haven't tried irc for awhile there are a lot of changes, like profile pictures, typing notifs, emoji reacts (thank me for this), built-in image upload, persistent presence, history, push notifications (no more making your phone lose battery while connecting!) and dozens of other changes.
@jc0b there are dozens of "discord clone"s these days, but i honestly couldn't recommend any of them. if you're making an open source implementation trying to copy a big company you're obviously going to lose to that company. communication programs don't just need to be open source, they need to be based on standard, well-tested protocols with a diverse set of implementations. so in my opinion that basically leaves irc and xmpp.
i work on irc because it's the classic implementation of chatrooms. it's incredibly easy to parse (i wrote a bot in 200 lines of awk) and it's so lightweight and modular that you basically never get forced into paying one company to host everything.