Perhaps the Shroud is a Medieval forgery, but detailed photographic and spectrographic studies in the 1990s failed to show evidence that the image was painted. There were many “holy relics” during the period and those that survive are easy to detect fakes using modern analysis. Even a clever forger in the 1350s would have had to go to painstaking lengths to create the image on the shroud and what we know of the knowledge and technology of the day such an image might well have been very difficult if not impossible to create. It also begs the question as to why would a forger have gone to such lengths in creating the shroud when far lesser efforts would have been more than sufficient to be believed at the time. The confession by the supposed forger while interesting may have been done for political reasons perhaps like a 14th century Steele dossier. The Medieval forgery theory would be totally convincing if it could be demonstrated how such an image could be created with the technology of the 14fh century
The ‘decretals of Isadore come to mind.
I don't think there have been any successful efforts to reproduce it using 21st century technology.