r/moderatepolitics was the worst for that.
Their moderation policy basically allowed any abhorrent view as long as it was expressed in a "civil" manner.
Trolls and racists could say things like "well, in my humble opinion, black people are just inherently violent and unintelligent" and anyone who got irate and called them out would get a warning and/or banned.
It's generally easier on the kids in Thailand, I think, because mixed race couples are more widely accepted there than in Japan/China/Korea.
I did a few years teaching ESL in Seoul and out of hundred kids, there were just two siblings that were mixed race - Korean mom and American Dad.
Even though these two kids looked basically Korean (except their hair was dark brown instead of black) and spoke fluent Korean, I was shocked that some of the other kids in the class referred to them as 외국인 (foreigners), the exact same word they used to refer to me as white man.