Hi and welcome to the board. My supposition would be that the glass itself is made by one of the big French glasshouses, e.g. Durand or similar, and then shipped to Italy where it is decorated by an Italian company who then applied the label. The Made in Italy therefore would refer to the decoration not the glass... it's called being economical with the truth! Alternatively, labels may have been migrated from elsewhere. It happens, sadly sometimes deliberately, sometimes by chance.