This issuer has the modern PRC flag on it, which is then reused on a bunch of smaller, medieval sub-issuers (dynastic rebels, Tatar dynasties, etc.).
I think that the problem is that if a sub-issuer doesn't have an own flag, it just inherits one from the parent issuer. Which is in this case China, where the red PRC flag is appropriate. But it looks weird besides medieval coins.
The Empire of China, which is a sub-issuer of the Empire of China (section) has the Qing dynasty flag, which is also anachronistic for the earlier coins, but it's still better, than the flag of the PRC. It would be better to use the Qing flag for the Empire of China (section) too. After all, the China (ancient) (section) already uses that.
