Oh believe me, I can get ranty on this subject, too.
Ultimately, Fanime, like any other place, is filled with some great people and some crappy people. I'm a white female, so the amount of discrimination I face is negligible in comparison to the first poster, but even I have some negative experiences regarding con-goers and race. I dressed as Celty a few years back, and if you're unfamiliar with the character, the cosplay is a tight leather one-piece with a large helmet. It shows no skin, and I painted my neck to add to the "headless" look. As I was running to get somewhere, this guy approaches me and asks, "What race are you?" This is a question POCs may get all the time, but as an obvious white girl, I stood there confused at the question until he saw my wrist peeking through above my glove and said, "oh, you're white. Never mind." To this day, this is the weirdest interaction I've had in cosplay. Why my race matters at all, and why he felt it appropriate to ask a stranger that, is something I still don't understand. Likewise, my boyfriend (who's Cambodian and actually does get the "what race are you?" question all the time) dressed as the original Black Power Ranger one year. He lost count of the amount of times people asked if he was "really black" behind the helmet, and even more inappropriately, if he was "black down there" also. What the hell, people?
I'm also sick of the term "black version" of a cosplay. If an African American girl dresses as Sailor Moon, regardless of if she uses a blonde wig or her natural hair, she is SAILOR MOON, not a "black version of Sailor Moon." It's just straight-up disrespectful to the time and energy that she put into her cosplay to categorize it like that. I don't see us white people being called the "white version" of whatever Japanese character we're cosplaying, so why does it happen to another race?
One last thing regarding race that I've seen around conventions is the idea that "only X race can cosplay Y character." I love Garnet from Steven Universe (who, to be clear, is an alien gem and thus race-less), but I will never, ever cosplay her because I've seen people online tear apart white cosplayers for daring to cosplay her, equating them to racists for their way of showing appreciation for an awesome character. I would understand that mentality if someone were doing offensive blackface, but that's not the case here. Also, no one is taking a character away from any other group; literally anyone can cosplay anything they want. That's kind of the point of cosplay to begin with. I know that that's a very unpopular opinion on some parts of the Internet, but I don't agree with the belief that a fictional character can "belong" to a race.
People are just really, really weird about race. Still. That doesn't stop at the convention doors, unfortunately. We may seem to be a more inclusive bunch, but there are still just as many judgmental people as there are outside the con scene.