This couldn't be more wrong actually.
Xmpp is far from death. Just because many started to use matrix instead doesn't mean it's dead. Even though matrix is a Ressource and performance nightmare much more so than xmpp will ever be.
I'm an IT specialist and work in IT too. I also selfhosted a lot of stuff publicly.
XMPP is used by many companies like Facebook , Google, Nintendo, GitHub, zoom, WhatsApp, Apple etc.
Xmpp is a an official Standard.unlikr things like matrix.
And if you think that xmpp has battery issues.oeadays then that tells me you used any xmpp app like conversation/snikket etc. like many years ago.
My xmpp Apps use way less battery than any matrix app ever could.
XMPP is fast, reliable and just works. Matrix is a nightmare to selfhost, too.
IRC? Irc has no E2EE whatsoever. Therfore isn't even comparable to xmpp with omemo or matrix.