So, the problem is that Plex Web seems to change the saturation(?) of the image (screenshots, left one is plex, right one is potplayer, its also the same with vlc). The video is encoded with x265 so plex always transcodes it to x264 (sorry if its not important, im a noob :/) This issue happens on all devices BUT not on Plex Media Player (windows 10).
Also another thing, plex transcodes x265 videos while watching on my pc, but on mobile it plays in original quality. Is there a way I can do the same with my pc? (Also