The title lets you guess what this is about.
What I find particularly funny is that it does not seem to be due to the ambient lighting in the room. This is because when something dark appears on the screen (for example, a dark background), the screen gets darker, and when I turn on a bright wallpaper or window, the screen brightens up.
Do you have any suggestions?
Can it be that you have any programs installed that control the screen, for example, to protect the eyes?
But that would not make sense in terms of logic, since he would actually have to darken in light backgrounds xD
Have you set an AMOLED display or any energy saving modes?