Nowadays "buggy" is not how I'd describe it, though there were certainly teething issues at the beginning. By now other DEs have learned to deal with it.

However it's still true that the GTK4 design is ill-fitting, and very opinionated. Quite exemplary of this are the applications that hardcode the GTK file picker (like Firefox and chrome) even though it's inferior in every way to the Qt file picker and forces the infuriating GTK "design" choice of doing fuzzy search when you type in the file list instead of jumping to the relevant file. Very annoying when dealing with organized directories especially when no other file browser on my system works that way!