Why did the sale of indulgences become a critical issue during the Renaissance but not the Middle Ages

First of all reinassanc eis nto historical era its term coined in late 19 c for movement in art which was inspired be greco-roman style the correct term is early modern era, it become a critical issue that in late!5 and early 16 century sale of indulgences became massive enterprise which sometiems was conected to charity but ros to a massive scale