early 70's Columbia Burbank LP pressing question (Greenslade K46207)

Hi, thank you for accepting me. I joined because I have a question and most of the related questions (and answers) on google seemed to be on this forum.

I have around 2000 LP's mostly classical, jazz, OST, pop. I wanted to get a copy of the slef titled first album by Greenslade (K46207 from 1973). I have their second album(bedside manners are extra), like it and it sounds good.

I've now had two copies of K46207 , Columbia Burbank label with palm trees , which appear to be original 1973 gatefolds , and blemish free, but sound terrible , and both in the same way , bright & thin with a rather fuzzy sound. OK could be just the way its mixed , and certainly not really as I'd expect from a worn stylus.

What I find odd, and my reason for asking, is that if I look at the vinyl on both examples it's different to my other albums. the surface is clean, the grooves are VERY reflective, but there is no coloured "rainbow" patterns if I incline the LP to the light. With a clean record if I incline it I see greens and purples bands to the reflected light, which I *think* is light refraction from the groove walls. I see this on old albums going back to the late 50's through to recent albums. But this LP doesn't do this. Its very shiny, looks very clean, and ditto after I cleaned them, but the grooves seem somehow different. the first example I bought and played, I returned and half suspected the seller had somehow polished the surface to hide something, it was so shiny. However when my second copy was exactly the same, I wondered if there was something more basic here (assuming I hadn't bought the same copy again LOL - no different seller )

1973 was the oil crisis, and I wonder if these pressings were done on a different material. They are thin, but not exceptionally so, and I have much thinner albums which sound great.

is this familiar to anyone here ?