Euh I kinda get what you are saying, but it looks awfully confusing. The page is titled “The gnome extension” and literally reads
This is an updated version of the gnome-3-38 extension that will only work with the core22, built from Ubuntu 22.04 LTS.
So as a random reader I’d reckon the page is just about the Gnome extension. There’s no indication it’s somehow about core22 (or any other core for that matter), and it’s also not clear the page is about a successor to gnome-3-38 (which is what you’re hinting at I assume).
Anyway, I’m totally lost in this “core vs gnome” versions conundrum, and I’m just unable to build Ymuse as I fail to find a working combination of core-gnome-gotk3 flags… 