Any difference by switching between 2160/1080 in Kodi system settings?
Yes, there is a difference but just a bit better. When I use build in player and play the same movie from the same source (NAS over DLNA without any transcoding) or from USB, the picture is better and there is no over-saturation.
Also, when I switch between full hd and UHD settings on android Kodi, there is no difference in saturation.