I had a quick question around the “Fallback kernels” and what is being presented. I recently switched to the 5.8 Kernel and when I boot up (in Grub) I see the following:
Your picture is not showing a “fallback menu” but the regular grub menu. And this menu shows all installed kernels. In your case 5.8 and 5.7. And for each kernel you see two entries. The entry with “fallback initramfs” in the name means that this kernel starts with a more failsafe initramfs. Just in case you mess up your initramfs with mkinitcpio, the “failsafe” kernel might be your rescue.
Just a few words / recommendations regarding this topic:
Kernel 5.7 is basically end of live. Very soon you will not receive any updates to this kernel anymore. This makes it a bad choice as a kernel to keep installed. You should rather think of installing kernel 5.4 which is a log term support kernel. Just in case kernel 5.8 breaks for you, the LTS kernel is a good fallback solution.
Just to give you some background on “fallback initramfs”. These images contain many drivers that are not necessary to start your system at the moment. The normal Kernel images contain just the driver that are necessary to boot your system up.
But if you change your Hardware you might need different drivers to boot. The normal images might fail to boot up. The fallback contains these drivers and let you start your system.