Card or holder issue?
 

This is not my card. It is for sale on ebay.

What do you think is happening in the upper right corner? It looks like the surface of the card has deteriorated and flakes have spread throughout the holder. Does this happen with some types of cards? Is it something about the holder?

Oops looking at wrong thing.

Moisture damage. The card got damp/wet and then friction between card and holder caused flaking damage. M101s are not prone to this any more than other cards, although it should be a rare occurrence when moisture gets inside the holder. One would hope.

It might have just been something on the card before grading and over time it deteriorated the paper.

Thanks, guys. Moisture damage makes sense, perhaps something that even started in a small way before the card was slabbed. It just seemed so striking to see now, because it must not have been very noticeable when it was first slabbed (to get that grade).