Okay, maybe two or three weeks ago, there was a massive update, tons of GNOME (whatever it is) apps were updated. After an update, there were few visible updates like bar that you can pull from top of screen, and some other minor differences. But, there was also some problem. After that update, my screen brightness needs a second, second and a half maybe, to change, whether I´m using hotkeys on my keyboard, or by using my mouse and changing it. Btw, my current version is 3.3.19
Details 