Having looked at moving from GTK3 to 4, I can understand the frustration. I also read a bunch of stuff and have concluded there are good reasons for the disruption, from making things more generic which allows new combinations of widgets (like images in menus) to allowing stuff to be in a different process. That does not mean the migration or support for doing it was handled well.

I was also disappointed to see they talked about having major releases at a regular cadence, which luckily they are way behind. Stability is a very important feature for toolkits and other infrastructure software. I would argue that being cross-platform and having stability are the 2 most important features of GTK and I hope it's a very long time before GTK5 comes along - if ever. The other major feature is the C API which allows it to have bindings to many languages.