This is a bit of a longer story, I’ll try my best to keep it short:
Whenever the system goes to sleep/hibernation and wakes up, NVIDIA hooks those events using /usr/lib/systemd/system-sleep/nvidia and directs them to their script /usr/bin/nvidia-sleep.sh.
When entering sleep/hibernation, the script is called with argument suspend. It will then switch to a certain virtual terminal and issue a suspend request to the driver.
When waking up, the script is called with argument resume. It will then issue a resume request to the driver and switch back to the virtual terminal that was active before entering sleep/hibernation (i.e. usually the vt running X11/Wayland).
Now, on my system, I noticed that said script never gets called when entering sleep/hibernation. Services /usr/lib/systemd/system/nvidia-*.service should do that, but they don’t on my system. I’m not overly familiar with systemd, maybe those services just need some additional configuration?
Anyway, to quickly fix this, I simply patched the hook to perform both operations:
#!/bin/sh
case "$1" in
pre)
/usr/bin/nvidia-sleep.sh "suspend"
;;
post)
/usr/bin/nvidia-sleep.sh "resume"
;;
esac