If you use the 5.3 kernel with a Debian Buster install ( ie: Proxmox 6.1 ) you will find that the kernel module for the nvidia driver version 418.X fails to build.
Fortunately it’s an easy fix.
First you need to create a file in your sources.list.d directory:
echo 'deb http://deb.debian.org/debian buster-backports main non-free contrib deb-src http://deb.debian.org/debian buster-backports main contrib non-free ' > /etc/apt/sources.list.d/buster-backports.list
Then you can just reinstall the nvidia dkms package with
apt -t buster-backports install nvidia-kernel-dkms
Pay attention to the warning about the incompatibility of some video cards with this version of the driver and adjust accordingly.