"The Australians’ study has found coins that represent Pope Johannes in the mid-850s. They were dated based on a stylistic and graphological examination of the coins. The coins had been inscribed with the name of Pope Johannes Anglicus. This was the name that the female Pope used according to the medieval narratives. Moreover, there is a distinctive monogram on the coins and these could be based on the signature of the female pope."
https://www.ancient-origins.net/news-history-archaeology/female-pope-0010644
So every single thread on r/askhistorians says that pope joan is a myth so I did some googling on ancient origins.net
So apparently its a very fringe site that loves conspiracy theories like aliens
So yeah
Edit: also the only article on google about the 'discovery' of these coins are from ancient-origins.net