I think someone (not me; I do this too much) should file a bug report about this - here. I note that there is a corresponding message when use uses apt (or apt-get) in the terminal, except that, in the terminal, the message is tagged as a warning, whereas here it is tagged as an error - which makes the situation more serious. Source: almost 2 years ago

I don't think the Mint team has said. All that the team has said, to my knowledge, is that some of the 20.2 update will be backported. One thing you could do to try to answer your question is to keep an eye upon the relevant repository. Source: almost 3 years ago

Next compile / install the AUR package https://aur.archlinux.org/packages/nvidia-390xx-dkms - I'd recommend using a helper app like paru to help installing updates for it easier. Reboot and the nvidia v390 kernel module should have loaded. Source: about 1 year ago

Many users also use an AUR helper, which makes it easier to install and upgrade packages from the AUR. Yay and paru are the most popular. Source: about 2 years ago

Paru-bin provides binaries for x86_64 and aarch64. If your device is not aarch64, you'll have to build paru from source. Source: about 2 years ago

I use paru as my aur helper. It uses the same flags pacman does with additional ones if you want to handle only aur updates instead of both pacman packages + aur. Source: about 2 years ago

You can get an AUR helper such as yay or paru to automate the process. Source: over 2 years ago