timdiggerm said:

I think what you're noticing may be described as "an imperfect film made by young filmmakers in the 1970s"?

Though I haven't seen the 1977 35mm, every version I've seen has inconsistent skin tones. GOUT/Harmy/Blu-ray/1997/etc. It's brought out to varying degrees in different versions, though. I think every version has scenes where skin tones look unnatural. Not always the same scenes, depending on the correction. But I think timdeggerm is probably right and it's inherent in the film for whatever reason.