I think the main problem with IRCv3 is that there are a million optional extensions (see https://ircv3.net/software/clients for a feature support matrix of popular clients)
This can get especially confusing when people on different clients have divergent views of the same conversation. e.g. some can see the emoji reacts, others can't. some can see "replies", others can't.
This can get especially confusing when people on different clients have divergent views of the same conversation. e.g. some can see the emoji reacts, others can't. some can see "replies", others can't.