Leonardo was working with Optics and was quite the practical joker. He was also no friend of the Vatican.
The shroud is attested from well before Leonardo was born.
“He was also no friend of the Vatican.” — well, technically Leo lived from 1452 to 1519 and the Vatican city came into existance only in 1929 and St. Peter’s was only completed in 1590. So, I’m sorry but your statement even to make it “no friend of the papacy” is wrong