Ever since Google Talk stopped supporting Jabber, I quickly ran out of anyone to talk with. I talk with friends on Signal, I talk with FOSS projects on IRC or Matrix, and I occasionally set up ad-hoc video conferences using Jitsi Meet, but I have zero Jabber contacts left. If you use Jabber today, who are you talking to and on what server(s)?
XMPP for me is mostly internet friends. It's quite popular on the fediverse (they also happen to commonly dislike Matrix, although many are on both like me). Lots of people who are into technology and anime, basically.
I've noticed most free software projects don't have an XMPP room unless they are literally XMPP projects like Gajim and Dino. Pine64 (as well as many other places) will have a bridge between IRC and Matrix, but I've only seen one or two IRC channels that also bridge XMPP that I can remember. Many people aren't even really aware of it. I don't know the actual stats, but it often feels like XMPP is actually less popular than IRC these days.