Take a look. This is the s in pluribuS <— definitely thicker than any other I’ve seen but it’s only on the S. I’m still pretty new so if someone could explain what this is and how it classifies as that it would help me learn I could also be wrong and it’s just an old nickel
Looking at some of the other letters near it I would say that is an issue with Die Deterioration. IMHO
Each year for every denomination there are millions of coins struck. The Dies used do become worn and have to be replaced. They don't use only 1.