I have started using Signal for large group chats in the past year or so, after spending many years using it as an encrypted replacement for SMS texting. Signal has gotten noticeably better at the UX of group chats during that time, although I am still annoyed that they basically require you to use their client to access the network in the name of security. I can't easily run a legitimate 3rd party Signal client on my server, and when I've tried I've accidentally broken my access to my account on my phone, which is quite annoying since I use Signal pretty frequently.

I want there to be something like Matrix that is designed first and foremost as a large-group realtime chat program (really, as a meaningful FOSS alternative to Discord), and it should make different tradeoffs than Signal. I'm actually willing to entirely forego encryption, at least at first, to make this happen - IRC wasn't encrypted and Discord isn't either, and these are things I want to replace with something better. Matrix's UX is still noticeably worse than Discord's, and I'm skeptical that the ostensible security gains from the encryption are worth it, especially given the problems with device verification UX, metadata leakage, and the fact that as the number of people in a group chat grows the possibility that they will take a screenshot of the encrypted message sent to them and leak it to the press grows higher and higher.