With nVidia driver version 570.124.04, which is now the latest on RPMFusion, a system freeze can occur (it doesn’t always) when waking from sleep on a system with multiple monitors. One monitor goes black and the system freezes, requiring a reboot.
The journal (at least on KDE systems) shows an entry like:
kwin_wayland_drm: Pageflip timed out! This is a bug in the nvidia-drm kernel driver
This is not Fedora-specific - the problem as I experienced it is precisely the same one that this Arch user reported - but posting it here in case anyone else has the same problem and searches here.
It appears to be specific to 570.124.04 - users report that downgrading to 570.86.16 fixes the problem.