Which is one of the biggest problems with Wayland - there isn't just one Wayland but Gnome Wayland and KDE Wayland and wlroots-based Wayland and Gamescope Wayland. What functionality is available and working and using which API varies between all of these. This includes really basic things like window decorations.
This is different from X where the core functionality is common because everyone usees X.org. If all the Wayland compositors agreed on how thing should work then multiple implementations would be much less of a problem. But they don't or at lest take ages until all but one of the NIH protocol extensions get abandoned. Some of this protocol extension zoo is hidden by applications and toolkits implementing multiple variants but even if you no longer see it as an end user this is still a cost because time spent on dealing with Gnome or KDE bs is time not spent on more useful things.