that is only a color filter meant as a last resort for people who don’t know or don’t care about a proper hardware calibration in regards to the ambient light. most people use their laptops at night with extremely poor lighting conditions or very dark room or no ambient lights at all. they just rely on the keyboard illumination to see what they are typing but that is extremly harmfull for the human eye which is very sensitive to contrast and adapts to compensate but the end result is fatigue and deterioration.
without direct display panel hardware controls to brightness and individual rgb color channels there is little use for a hardware calibrator as it requires setting targets for measurements and characterisation/profiling.
for instance my 4k samsung non qled/oled TV which i use strictly as a monitor (i don’t feed it any internet connections) can barely touch the rgb brightness targets i chose. that is because it is extremly poor quality. the reds and greens are bellow the target point and the blues are above @ 120cd/m2 brightness. but without a hardware calibrator (mine is a colorimetre which needs specific spectral corrections from spectrometers) i wouldn’t be able to figure this out. STANDARDS.