Looks like it has some sort of gunky residue on it or corrosion. Try soaking it in some warm distilled water and see if any of that gunk dissolves. This is known as environmental damage. If you can clear off residue you have a fighting chance to save the coin. But if it is corrosion, it has eaten into the surface of the metal and that is irreversible…imo…Spark
There is corrosion on the obverse: On the shoulder above VDB and next to the last T/TRUST. But the only things I can think of where metal is bonded to metal is a plumbers solder, acetylene torch/welding splash or high heat has melted a foreign metal of some sort onto the coin. Either way it is PMD as @SensibleSal66 said…an altered surface that did not originate at the Mint…imo…Spark
Some kind of foreign substance on the coin, solder, epoxy, melted plastic, doesn't really matter what it is.
As mentioned, that’s glue residue or some similar post-mint contamination. Those rounded arc-like features show where other coins were once stuck to this one by the glue (or whatever the gunk is).
That didn't happen at the Mint, it's not a Mint error. How did it happen? I just collect them, I'm not a detective.
