It's hard to say. It appears to be post-strike damage, as there is faint and blurry detail from the original strike on the damaged surface; the denticles pointed out by Dearborn, in particular.
It may be a delamination. Or it may be post-mint damage: somebody attached something to the coin (or attached the coin to something) and tore it off afterwards.
The amount of wear the coin shows indicates to me that it's post-mint damage, on the theory that "if it came out of the mint looking like that, surely somebody would have noticed".
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis