Grub changes back to 420p dispite it being 1920x1080 in /etc/default/grub config file

[petsam]

@SGS

check what is possible, not what you like with

you can see them in real GRUB with the command `videoinfo’

Exactly.
Alternate method to videoinfo:

sudo pacman -S hwinfo --needed
sudo hwinfo | grep -C3 "Resolution"

https://wiki.archlinux.org/index.php/GRUB/Tips_and_tricks#Setting_the_framebuffer_resolution