Hello there!
I just updated my system and saw that Gnome 50 dropped, but I got the same problem that I have on Fedora 44 Beta that is a black screen after boot. Switching to Discreet graphics made it work, but it doesn’t on Hybrid graphics mode. I assume that is the same thing I got there, where the NVIDIA drivers work, since I can get Niri working on Hybrid starting it from a TTY and even gaming on it, but GDM and Gnome cause black screens.
Mind you that on CachyOS, is technically not a black screen, it’s the CachyOS logo screen and I can’t access the TTY without boot with on runlevel 3, on Fedora for a split second I can switch to an TTY. On both pressing the power button shuts down the system gracefully or CTRL + ALT + DEL restarts it gracefully, although it takes a while to start. On CachyOS I see my mouse cursor and I can control it, but nothing else.
[Edit]
As it is very annoying and wasteful to set my system to Discreet mode and that’s is getting in the way of me using Niri too, I’ll switch to another Display manager.
Discreet mode log:
Hybrid mode log:
[Edit 2]
On CachyOS a few Gnome packages updated to 50.1 (Mutter, Gnome-shell etc.) and now I can use my system normally again with hybrid mode enabled.