When I install the nvidia driver from
https://download.nvidia.com/opensuse/leap/15.2/ ffmpeg with nvenc does not work
as normal user. It does work under root.

When I install the driver directly (the so-called hard way) ffmpeg with nvenc
*does* work under a normal user account.

I see this when executing a command like:

ffmpeg -i input.mp4 -c:v h264_nvenc out.mp4

I found similar issues on the forum:

*
https://forums.opensuse.org/showthread.php/540150-NVidia-installer-broke-CUDA-support-for-Repo-driver

*
https://forums.opensuse.org/showthread.php/538981-Blender-and-Davinci-resolve-can-t-see-Graphics-cards-after-fresh-Tumbleweed-install