Comment 9 for bug 1933880

For me, with nvidia-driver-495, the simple solution was to remove the damaged symlinks from systemd. You most likely have them if you upgraded from nvidia-driver-470 or nvidia-driver-465, because 470 still included the .service files in /lib/systemd/system/. The files are no longer included in 495 but the postinst script does not remove the symlinks. So, remove them with:

sudo rm /etc/systemd/system/systemd-hibernate.service.requires/nvidia-resume.service
sudo rm /etc/systemd/system/systemd-hibernate.service.requires/nvidia-hibernate.service
sudo rm /etc/systemd/system/systemd-suspend.service.requires/nvidia-resume.service
sudo rm /etc/systemd/system/systemd-suspend.service.requires/nvidia-suspend.service

Works instantly, no need of rebooting or logging off.

According to user punyidea at https://gist.github.com/bmcbm/375f14eaa17f88756b4bdbbebbcfd029, the services are not needed on 470 either and may be safely removed.

Hope that will fix your problems as well.