She was supposedly, almost fired (https://www.amiannoying.com/(S(nyyswahs2odgghhpzot24xim))/view.aspx?id=5367&collection=761) over that (https://www.sitcomsonline.com/boards/showpost.php?p=5727343&postcount=21).

She held out because she thought she should make more money per episode. She is not the only actor in history to do that.

Contract dispute. After that episode, Nancy and the other girls gained a salary increase