I was experiencing similar issues with F38; a “phantom” monitor as well as GDM not fully loading, and being left at a gray screen, unable to login.
Using pkill gdm or systemctl restart gdm from tty 2 allowed me to login and add nvidia-drm.modeset=1 to the kernel line as noted by the OP.
From a brief search, it appears that whomever is affected by this will likely continue to require this workaround for quite a while, as it seems that kernel developers and Nvidia can’t seem to get together on this.
Mind in sharing the details on how to re-install the drivers? I’m still googling and most things I find either assume it’s installed by default, or don’t go step by step, and assume a log of Fedora specific knowledge. BTW: My issue might be cause I use netinstall (instead of Everything ISO)
I have noticed on a couple new installs that the nvidia-drm-modeset=1 seems no longer to be added into /etc/default/grub. If an older install already has it the option is not removed, but a new clean install seems to no longer receive that option in the kernel command line.
Don’t have a clue why it would change, but it seems to have done so from rpmfusion.