It is probably a "Thinned Planchet" since the strike seems unaffected tho weakened, the sign of thin planchets. This is where the stock plate of material has been rolled thinner than normal. If you weigh the coin, it will probably be less than the normal 3.1gr.
It is not that unusual of an error, so doesn't hold much value to it.

BTW
Edited by Crazyb0
05/03/2018 12:31 am