There is certainly also a device limitation. I would expect that with less than full 24 bits of color, some fields might just look the same and the results do n

There is certainly also a device limitation. I would expect that with less than full 24 bits of color, some fields might just look the same and the results do not depend on your vision any more. Let's say the device has a "24 bit color display". What about eye protection color shifting? This limits the color space used could reduce the effective remaining bit depth. Or maybe they do temporal dithering to get more bit depth? Or maybe the 24 bits are already achieved with temporal dithering? It does not need to be a calibrated display, but a cheap tablet in sunlight will be worse than a color grading monitor in a reference environment. I hope they also register the devices used and analyze the statistics on that.