It’s a four factor test. You can lose on one of the factors and still have it be determined to be fair use by a Judge, but if the Mona Lisa were still under cop

It’s a four factor test. You can lose on one of the factors and still have it be determined to be fair use by a Judge, but if the Mona Lisa were still under copyright (shouldn’t be, but we’ll use it for this example anyway), then per Andy Warhol Foundation for the Visual Arts v. Goldsmith, it would likely turn a lot on whether you commercialized it and whether it affected the market for the original.