What's evident in the picture to you to so confidently surmise its lead? The high points of the coin seem to reflect light a lot better than the lackluster quality of lead.
I've seen this finish on coins metal detecting in beach sand. Then whoever found it took a tool to scratch off whatever gunk was on it. IMO
If it started out as a real coin it was mutilated and put in an acid bath, IMO. If was a fake, it probably couldn't pass as real, so it was mutilated and possibly acid treated, too. IMO.