Hello, eh? It's too far away, need to sit closer. Maybe today? Also, what kind of coin is it? Please be more specific please? Sorry for all the questions. Not much to go on here.
I think it look more like a struck through wire or some string possibly. The line looks deep and there is no displaced metal along the edges of the groove. Is the heavy line also on the inside vertical sides of the coins rim? Do you have a photo of the coins edge where the line terminates?
I’m tired so not seeing to well but it looks to me like the Planchet had a crack before it was struck. This even goes through the rim at 2 and 6 o’clock.
I can not say definitively what your coin may be worth, as such a thing will and does vary with each person you might ask. If you can or a buyer can verify that it is an error it should have a value to some collectors, but I would not be one of them.