Could this be a d over s? Because the rim looks like a proof it's flat& square not rounded over. What do yall think?
Looks like your coin is suffering split plating under the SE edge of the mint mark. When the plating splits, then the zinc starts to deteriorate, disfiguring that area. I've seen this before many times. Not a OM. The "S" mint was on the proof coins this year and yours is not a proof coin.