IIRC gdm is already known to not work with xorg any more
You probably mean specifically gdm3, as gdm vanished over a decade ago (but there are gdm3, libgdm-dev, and libgdm1). GDM3 and xorg is exactly what we use on the machine in question running Debian trixie: gdm3 48.0-2 libgdm1 48.0-2 xorg 1:7.7+24+deb13u1 gnome-shell 48.7-0+deb13u2 Does your statement above refer to higher versions of gdm3 and xorg in testing/unstable/upstream?
So let me suggest to switch to wayland and assuming that doesn't work, […]
“suggest switching” :-) We tried Wayland a couple of times in the last 5–6 years. In my recollection, 2–3 years ago, Xorg was forced for our graphics card via the udev rules (which, in my recollection, were quite coarse at the time and ruled out quite a huge class of NVIDIA cards, if not all of them). On our last attempt early this year, Xorg was no longer forced, so Wayland tried to get started, but the initialization of the graphical user interface (probably GDM3 or some routing preceding GDM3) kept restarting itself, so even switching to a plaintext console was difficult. We finally succeeded to run Wayland: to this end, we added the boot options `nomodeset` or `nouveau.config=NvGspRm=0`, but the former resulted in poor resolution, and with the latter we got so many repeating error messages from nouveau in the log that we decided to switch back to xorg. We could retry Wayland once newer versions of the aforementioned packages arise. We will be able to report here, but I think the Wayland issues deserve a bug report of its own (against which package?).
