Comment 46 for bug 1777378

I believe I have found the culprit. Not happy to say that it looks like it was a configuration change I made to try to fix the ubiquitous screen-tearing and frame synch problems that some applications have. I *believed* I had reverted all the changes I made when I saw they hadn't fixed the issue, apparently I missed one. Oddly, the machine had booted up into a proper GDM session several times since that attempt. In any case, I went back over my research and double-checked anything that we hadn't already covered and found an article about adding a zz-nvidia-modeset.conf file in the modprobe.d folder. This had one working line in it:

"options nvidia_drm modeset=1"

Once commented that line out and updated initramfs the machine was able to make all the way into the full GDM session again.

I am very sorry to wasted your time on this problem that was obviously due to an oversight on my part.