If you are running default kernel with your Ubuntu or Linux Mint installation, you probably won’t face this problem during kernel updates because all packages are coming from the official distribution sources. However, if you like to run the newest Linux kernels and update them using mainline kernel installer, you may get warning possible missing firmware during the installation.

Few days ago I got this warning on my Linux Mint 20.3 Una while installing kernel 5.17.7. In most of the cases this warning won’t affect normal functionality of your Linux machine, but if you hate warnings, like I do, here is what you can do. I guess you regularly update your apt packages, but still new kernels may complain, which further means you may need even newer package. In my case I had to install linux-firmware package from Jammy Jellyfish , the newest LTS Ubuntu, Ubuntu 22.04 LTS.

sudo add-apt-repository "deb http://ca.archive.ubuntu.com/ubuntu jammy main"
sudo apt install --fix-broken
sudo apt-get install linux-firmware
sudo add-apt-repository --remove "deb http://ca.archive.ubuntu.com/ubuntu jammy main"

So, first add jammy repository (temporarily), then fix broken dependencies, install the bleeding edge linux-firmware and remove the repository if you don’t want to update any other package. You may also want to reinstall your newest kernel and find out that there are no such warnings.

Buy the way, in the meantime kernels 5.7.18 and 5.7.19 are released, but my Intel AC 9560 won’t work properly, so I skipped them and wait for some further version to find out if this is fixed or I need to do something about it myself. I may update you about this problem, so let’s stay in touch.