I've been hosting a server without much problems for several years now.

Synapse and Riot.im (now Element) became much better around 2019 or 2020. But not too long ago, I also found out that Synapse also bloats the DB with state_groups_state table. There are a handful of commands that come with synapse, but no built-in admin tool or panel, so I wrote my own. Moving server to another host has been seamless for my (few) users. TURN/STUN for calls seems to work okay (I don't really use it though).

I appreciate Element being uniform across platforms (which I cannot say about XMPP clients), but the sign-in is pretty tedious, and registration with a token is still impossible last time I checked (which is either a hassle for the user to use another client and then their smart device, or a security issue if you open registration to anyone). Most normal people probably don't care and don't want to deal with keys, cross-verification, and all that jazz.