I always were able to use the brightness keys f2 and f3.. had an auto update and couldn't adjust, screen is dim but somewhat visible
I cannot addess the " f2 and f3 " issue.
In my
laptop, I can press the Fn key and then press the brightness Left or Right key to make changes.
I never own a desktop computer. So, I don't know what is the difference in the keyboard setup.
However, have you tried to go to Settings > System > Display > on the right side, under Brightness level, move the slider to adjust the brightness ?
Granted that is not the same as you can change brightness on the keyboard.