@mosm, first welcome to CCF. Second, I agree that the surface of this coin looks stained, perhaps from being in a liquid. We see coins that have been sitting in car cup holders, but as @ijn, points out there are plenty of possibilities. In any case, this coin didn't leave the mint looking like this.
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz