Where does it say they are upscaled ? That link you gave me to that web page is really bad.
The Groundhog 4k Netflix film is meant to be a transfer from the 35mm original which has been discussed before here and on other forums in that the 35mm original has enough detail to be transferred to a 4k digital film.
Its quite easy to follow. And im using a mobile . Just bump the choices to tge max and scroll through. Clearly says upscaled