I can change my screens too on desktop, pretty neat.
Unfortunately its a super simple implementation which doesnt take into account the brightness between different screens.
Ideally there should be a master slider and one per screen. The master slider should then use theother sliders current value as scaling factor to change them.
A more complex option could then also allow setting the brightness of each screen which would allow for better setting via the master slider. (not sure if this information is already available)
DNS filtering only gets you so far. Its far, but certainly not at the end of the road. More complex and differently designed systems wont be bothered much.
Encrypted DNS or simply hosting legitimate stuff on the same domain cannot really be fully blocked entirely or make your life difficult.