This article is about Zernaki Tepe - in what is now Turkey, but 1700 years ago was on the borderland between the Roman Empire and Parthia/Sassanid Persia.
Mithra is a Indo-Iranian god.
HOWEVER, Mithraism in the Roman empire was different from the Indic or even the Iranic worship of the same named god - in many ways it was a different religion.
In the Roman empire, the Mithraem was basically a man’s club (think of the Flintstone’s warthog club) - so we don’t know the exact details of this, but it was mostly guys hanging together. it also wasn’t inspiring per se, which is why it died out.
This article is a nothingburger - nothing really new. the site was abandoned by the Mithra-ites long long before Christians met in this place
“the site was abandoned by the Mithra-ites long long before Christians met in this place”
That’s not what I read. The ascending Christians and the Roman Emperors who made it the official religion intentionally buried old pagan worship sites.