Not sure what exactly happened to that nickel, but it is just PMD. If it were struck through grease or something else, it probably wouldn't show up on the other devices, like the E T and under the D in GOD. Most likely something spilled on it. NAV
I think it is a Struck Thru Grease coin as the abnormality follows the contour of the inside edge of the coin at the lower right side of obverse. And having move than one spot is not uncommon for STG That much PMD would/should have also damaged the face edge of the coin.
I think there is a good chance that you are right about the grease strike through. I'm not seeing any die chip or break at the base of any of the columns.
APPEARS TO BE STRUCK THROUGH GREASE, MAYBE WORTH 5-12.00 ON EBAY, OR USA COIN BOOK, IT IS A NICE EXAMPLE...WHERE DID YOU GET IT??