I think, this ⅔ Taler is one and the same type as ⅔ Thaler from Saxony (https://en.numista.com/192089). Minted in Leipzig (or Dresden) for Friedrick Christian, who was elector of Saxony for a short period (1763 Oct. 5 to Dec. 7) and was never ruler of the Polish-Lithuanian Commomwelth. I suggest to delete this page and add the specific information (e.g. Kopicky no., punch differences) to the Saxon page.
This problem may apply for all the five Polish coins of Friedrich Christian.