PVC Damage?

I have a bunch of coins in flips and I don't know if they are PVC or Mylar.  I'm wondering if the toning you see on this coin is PVC damage.  What do you all think?

Doesn't look like damage to me.

My guess, looks like remnants of a well earned patina that was destroyed by cleaning. The rainbow colors between the cleaned part and the old patina could be from the chemical used to damage the coin. Maybe you can shed some light on what the coin has been through?



Can't do much else, maybe you can add a sharper photo, then we can see more.