Pretty much every Linux desktop GUI's been on top of the X Window System—which has been synonymous with the Xorg implementation thereof for, oh, 15ish years now—until very recently. Red Hat's behind a totally different replacement for X Window (and so, Xorg) called Wayland, but desktop environments that run on top of X Org will require major work to move them over to it, and most haven't done that yet, if they ever will. Last I checked Wayland's also a bit half baked at this point, from a "does it work with all my stuff and do all the things I'm used to" perspective, so news that it's the only system receiving new feature development means some risk of a fairly awkward transition period.

Notably, I think you still can't get hardware acceleration under Wayland for nvidia cards, making it unusable. Yeah that's nvidia's "fault" but to the end user it makes no difference if they upgrade their distro, the distro switches from Xorg to Wayland, and suddenly their computer sucks.