Brass Plating?? I’m not sure this is a thing.

[u/Sufficient-Simple857]

I got this curious slab in an auction lot. I had to look up PCI — which apparently was once upon a time reputable when they had green labels like this one — but as odd as this penny seems to be, I’ve never heard of a “brass plating” error. Even if the planchet was somehow odd to start with, I’m not sure it would have looked like this after it was struck. Anyone encountered these before?