Wayland

Some people don't even know if they are using Wayland graphics instead of X window system. If that is your case, how to check? usually is as simple as check the output of the command echo $XDG_SESSION_TYPE. The output will be x11 if you are using X window system, wayland if you are using Wayland graphics or tty if you are running a headless system. Sometimes this var can also be empty, but in that case probably you are not using Wayland.

In order to work with Wayland graphic system (instead on using X window system), you must add permissions to root user in this way:

~$ xhost +SI:localuser:root

Doing that, root user (or using airgeddon as sudo) is able to detect the screen resolution flawlessly.

More info about Wayland graphics system at Wayland official's page.