Low video brightness at boot

After selecting the grub option the screen brightness reduces. Both on battery and with power on.

Sorry to bother you. Found the brightness setting under the battery icon in the panel.

I don’t know which desktop environment you’re using, maybe useful to know with KDE you can define 3 different brightness levels dependant upon power source:

(KDE) System Settings -> Power Management - Energy Saving

On AC Power, On Battery, and On Low Battery.

I guess other DEs may have similar settings…