You know it's funny. Awhile ago I subscribed only to watch Stranger Things, I paid for the 1080 HD plan.

4K is clearly incentivized. Any how, I called to complain at the time. My opinion is the picture instantly got notably better when I tried standard HD again. There seems to be different degradations of 1080 and 4K.

Resolution is easy to see, but what you really want to pay for is the bitrate.