The problem is that if a “random person on the internet” can substantially improve upon what is supposed to be a painting 100% executed by Leonardo da Vinci, than that is NOT a real da Vinci.

I should not be able to improve upon da Vinci, and I can’t. But what I can do is improve upon an overzealous retouching job performed on a severely damaged painting. And this is the crux of the matter. This retouched version does not look like a da Vinci, and is nowhere near his level of competence. It contains conspicuous amateur errors which are due to the restorer having to recreate missing and damaged passages. However, the painting was sold as if Leonardo painted that face, when in reality, the only parts that were well preserved, and convincingly…