So I bought a polarising filter yesterday that has a dial you can turn to increase/decrease the polarisation effect and mount directly onto the lens. I also have an old polarising filter that was one that you mounted in a rectangular filter holder. By coincidence, I'm doing polarisation in physics at school at the moment, so understand the concepts.
Understanding that my phone screen outputted polarised light, you could turn my old filter around in front of the screen and watch it go from light to dark, then light then back to dark etc... It worked both ways, so if I flipped my filter around, the effect would be the same. So I try it out with my new filter, and begin to rotate it - the effect is the same as the old one as expected. However if I flipped it over, the effect was not an increase/decrease in brightness, it actually made the screen go from warm to cool, then back to warm then to cool as you rotated it (i.e. orange to blue).
I don't understand why this happens - surely it should work both ways like my older filter?
My phone is a Samsung Galaxy S8, so it has a Super AMOLED display.