I agree with a better pic needed, but it does just look like environmental staining.
The following scenario is also a very good possibility, though the nickel shown is worse off:

The following scenario is also a very good possibility, though the nickel shown is worse off:

How much squash could a Sasquatch squash if a Sasquatch would squash squash?
Download and read: Grading the graders
Costly TPG ineptitude and No FG Kennedy halves
https://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2
Download and read: Grading the graders
Costly TPG ineptitude and No FG Kennedy halves
https://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2