Looks like silvering to me
Definitely!It’s really prevalent in Jungle and Fossil as well. I opened up some 1st edition Jungle packs not too long ago and straight out of the pack, the holos still graded 9’s because of the silvering.
The PSA case would protect it from spreading further. The main cause of it was manufacturing and improper storage of the sealed pack / the card.
I don’t browse that much but the last time I looked at some PSA 10- Jungle/Fossil/Base cards, they all have silverings.
Silvering on the edges shouldn’t affect the grade except a a tiebreaker…maybe.