Edit: Replugging the laptop to the power supply fixes the problem, manageable, but still somewhat annoying.
My Acer Aspire V Nitro (Aspire VN7-592G) has it's display change brightness based on what is present on the screen (white makes it brighter, black makes it darker). This does not change the brightness value in Windows, only some hidden value I can't access. Changing some system registry value worked, but after a while it started again, and the registry value wasn't changed. I tried different values, but it still keeps happening. I've tried changing power settings in intel's graphics properties software, but this always reverts it to its default value after a restart, and it doesn't change anything either.
Windows 10 Home 64 bit
Intel i5-6300HQ @ 2.30GHz, turbos to something
Nvidia GeForce GTX 960M