Hello! Can we see the whole coin please? Looks like a "plating issue" but I can't be certain unless we have more Pics. SORRY.
Looks like a plating issue to me. If the D were doubled or even with machine doubling, the "extra" part of the D would be raised above the field. I would guess that if you look at it closely it is either lower than the field beside it (copper plate missing there) or, if raised, bubbled up slightly, caused by corrosion of the underlying zinc.
Agreed, split plating: https://www.error-ref.com/split-plating/ Technically a plating error, but exceptionally common I believe.
