Matrix definitely has its problems. Recently I've moved to a private matrix install and a lot of the issues I was having went away. I think the matrix.org domain is overloaded and has a bunch of weird errors because of it. If your account or rooms are hosted there and you have issues I'd try running somewhere else and see if you have the same problems.

Like someone else said the clients have issues too. A lot of them don't know how to report the errors they run into so they spit out garbage. There isn't a single client that works perfectly but there are a few that are good enough to use if you aren't using them for mission critical communication. It's stupid but it is what it is.

Discord sucks ass and no one will convince me otherwise. I have no desire to support them and their constant nitro spam. I'd rather use something like matrix and see how it develops.