Ive tried several linux distros and whenever I log out or when the computer sleeps cuda support disappeares leading to super long cycles renders. Is this a bug in blender, motherboard or linux? Id love to fix it.
Hard to know since not many people have that kind of problem. If you installed the driver from the distro packages repository, you should report this first to your specific Linux distro bug tracker.
Have you tried Pop!_OS or Ubuntu?
What is your GPU and what is the nvidia driver version?