well-worn, and maybe colored years ago, and it's wearing off. It's not an error of any type, in any case. Also called 'enviornmental surface' damage.
There was another pink nickel earlier this year! Here was my response - It means that the Pink Panther onced owned it!
Here was the thread -https://www.cointalk.com/threads/what-does-it-mean-when-you-have-a-pink-nickel.319130/ @Shrews1994 Remember this?