Look at that beard!! What a great looking example. Congrats bats.
Almost looks like ren wax may have been applied. If it were mine I would take the acetone approach first, followed by xylene if acetone doesn't do the trick.
Given the way PCGS
had been lately..... if you picked up on the residue, I'm sure they will and will more than likely give it the Details. If your ok and accepted it as a Details coin, leave it be. But I'd go the acetone, xylene if necessary route. My 2 cents.