Use Mainline to install the latest kernels
apt install mainline
mainline/focal,now 1.0.15-0~202110201909~ubuntu20.04.1 amd64 [installed]
Kernel Update Utility for Ubuntu-based distributions
Create an alias to download and install the latest linux-firmware.
alias updatemodules = 'rm -rm ~/Downloads/linux-firmware || cd ~/Downloads && git clone https://kernel.googlesource.com/pub/scm/linux/kernel/git/firmware/linux-firmware.git && sudo cp ~/Downloads/linux-firmware/amdgpu/* /lib/firmware/amdgpu && sudo update-initramfs -k all -u -v'
From there you can use the latest kernel with the latest firmware installed.
Enjoy.
