Ubuntu 21.04 Wayland, GIMP black window

Using Ubuntu 21.04 Wayland, when start GIMP, shows GIMP black window, it starts, but does not render decorations and widgets...

Just a black window. And GIMP is not the only one...

Even lxqt-sudo the same black window, but with new environment variable add, it starts working normally:

QT_QPA_PLATFORM=wayland

And for example:

Using Ubuntu 21.04 X11, start QtCreator, compile a project (first comment QT_QPA_PLATFORM=xcb and restart) and it open in X11, everything OK.

Then restart in Ubuntu 21.04 Wayland but compiled project does not run... After sudo apt install gnome-shell works in Wayland inside a window like Weston...

Any explanation for GIMP, still black window (what is missing?)...

Temporary solution:

GIMP works under X11:

sudo nano /etc/gdm3/custom.conf

uncomment: WaylandEnable=false

in nano only: Ctrl+X / key Y / Enter

sudo nano /etc/environment

add or change to: QT_QPA_PLATFORM=xcb

in nano only: Ctrl+X / key Y / Enter

Reboot to X11...

If want to go back to Wayland:

sudo nano /etc/gdm3/custom.conf

comment: #WaylandEnable=false

in nano only: CTRL+X / key Y / Enter

sudo nano /etc/environment

change to: QT_QPA_PLATFORM=wayland

in nano only: CTRL+X / key Y / Enter

Reboot back to Wayland...

https://phoronix.com/scan.php?page=news_item&px=GIMP-2.99.2-Released

Finally released a beta with Wayland support, GIMP 2.99.6 (2021-04-26):

https://www.gimp.org/downloads/devel/

And with instructions to swap between stable version (X11 2.10.22-3) and beta version!