Wayland has been working for a long time on the 3.x development releases. I run a wayland only (no xwayland) system, and I have been using GIMP development releases without issue for years.
Beta builds are working on Wayland for me.
There's a difference between Wayland support and working on Wayland. They're asking about actual wayland support, not xwayland, which presumably was never and issue
The beta builds don't use XWayland.
Where did I say Xwayland? It's 100% using Wayland, works perfectly for me.
Have you tried not using a monolithic display server?