There exist several clones, but they all have some drawbacks. Unfortunately few people are willing to tolerate them.

Fluxer.gg is really good and in my opinion, tries to be the most similar alternative to discord in terms of UI/UX so it should "just work"

I highly highly recommend you checking it out, I must say that the first time I used it, I was mind blown that this open source discord alternative actually feels so usable in day-to-day lives.

There are many alternatives to be honest, stoat, matrix,fluxer but fluxer is the alternative I would recommend for public spaces.

The issue now is I think mostly just moving the userbase over to there.

[I have talked to the dev and tried to share it a few times on hackernews as a submission to help get more userbase as I think that HN would definitely love fluxer if it came to know more about it]

(Very slight advertisement but I have tried to build something in this space at https://mirror.forum which can allow a community to have discord,fluxer,matrix,stoat links in the same place for the purposes of discovery of servers in other places than discord and also for the migration of the userbase itself as i think that the problem of an open source solution is mostly solved and this was my attempt at trying to partially help in fixing the moving the userbase issue and making people more familiar with alternatives, though the website mostly has no activity nowadays and I would love activity to happen but I am unsure how to realistically approach so... that's why I am advertising perhaps, I would love to get feedback as well :-D)