nvidia is currently partially incompatible with linux >= 5.9  . While graphics should work fine, CUDA, OpenCL, and likely other features are broken. Users who've already upgraded and need those features are advised to switch to the linux-lts kernel for the time being until a fix for nvidia is available.
nvidia 455.28 is incompatible with linux >= 5.9
2020-10-21 - Sven-Hendrik Haase