I think this issued can be closed.
In fact it is a really sad story.
Problems occurred at i915 classic. Xwayland upstream didnot want to
remove the activation of ES 2.0, which totally was not working.
But they also did not want to approve merge-requests,
which solve the problems.
Then Debian was delivered without the i915 driver, because upstream
decided to stop support for it @#$. Also gnome-shell was not working,
without an i915-driver (solved).
Finally Debian was delivered with the gallium-i915-driver. But this
driver surprisingly supports GL 2.1. And Xwayland disables glamor
at GL 2.1, because the graphics-performance is to poor.
So currently Xwayland uses the llvmpipe software driver again at
trixie (testing) and I think also at bookworm.
At the moment I use
https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1171 at
Xwayland, which also still is not approved. This patch activates glamor
for GL 2.1, and also uses some (fast) fallbacks.
This also needs Mesa MR
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25533 for i915
gallium, which
gives errorcodes if shader is failing, instead of using a standard
simple shader,
which mangles the screen.
