Seinfeld went through one round of reprocessing for 1080 HDTV and the word is that Netflix is doing it again in 4K before they begin streaming it.
Also Netflix's obsession with 4K is slightly anti-scientific and counterproductive imo. They are really boxing in their content creators at times, plus 4K can't be resolved in a reasonably large television at a moderate distance from a couch anyway. 4K is the dumbest thing. There's one cinematographer who said for viewing even 1080p was pretty good, and hardly distinguishable from 4K - for CINEMA screens. HDR is cool tho.
Seinfeld was shot on 35mm film so bully for them. The HD versions are interesting. You see parts of the set that were meant to be hidden in 4:3. You also see a lot of makeup errors. Once you see where the makeup ends on Elaine's hairline you can't unsee it.
I hate when they do that. I can’t watch the HBO HD copy of The Wire for the same reason. The whole point of cinema is you choose what the f** is within the frame. That’s literally PART of the art form, and an integral one at that.