Color quality low when playing web videos

Anytime I am watching videos on Netflix or Youtube, I noticed that the color quality is extremely pixelated although the settings are always in 1080p. My internet connection is very good and the resolution is fine, the problem seems to be with the color, especially in dark settings. I attached this image to see what I am talking about. The problem is a lot worse when it's in full screen but if you see the boy's face, the color is pixelated along with the wall behind, but the bed sheets seem to be fine. This is the latest version macbook pro and is only a couple months old, so why is the quality so bad?

Edit: I attached another screenshot which shows the problem more exaggerated. When full-screen the scene is almost unviewable.