Went to my first renfaire this weekend, was surprised by the costume policing by fair-goers

Went to the Washington midsummer faire this weekend with a large group of friends. It was a pirate themed weekend, so we dressed as pirates.

My brother in law is from Turkiye, he dressed as an ottoman era Corsair. At least 10 times over the course of a day and a half various people came up to tell him it was cultural appropriation to dress the way he was. My brother in law has brown hair and blue eyes , but many Turks look like that

I also dressed as a Japanese pirate and was reprimanded by white women for cultural appropriation (I am biracial black/white).

Is this the norm at renfaires? Are only European style costumes are acceptable? The experience made me not want to go back.