Ok as no one else is commenting, I will. My very amateur thoughts, partly because I was taken in a while back by a forgery which the experts here helped me identify and which had slightly similar characteristics.
I wonder about the smoothness of the surface of the blank area of the flan. Is it too perfect for such an old coin? The three Byzantine follises I've got don't show that same characteristic. If it was gold which doesn't corrode I'd be less less troubled by it but with this, I'm not sure.
As I say, I'm not an expert, just someone returning to the hobby after many years, with lots to learn. I'd still be interested to know what others say.