Yeah, it's due to ignorance and lack of exposure. Not malice.Funny enough, I am a 3rd generation Chinese American, and my girlfriend is Spanish/Catalan from Barcelona. I just see this and the Serbian team as silly and innocuous. In western and central europe, people don't have to deal with many other cultures other than your own. I'm sure in the grand scheme of things, they are waaaaaaaaaay more socially and culturally sensitive than China. Take my anecdotal experience for what it's worth, but I've had wonderful times partying and making friends in Spain and places like Croatia in comparison to China.
I know even being American and Chinese, and not speaking Chinese, people in China are very overtly rude towards me. There's a word or something like 'useless Chinese' that gets thrown around. That's pretty prejudice.
We live in a world where somebody literally defaced Lebron James' house, the most famous current American basketball player, with a hateful, and purposely hurtful racial slur. That's where the real dangerous racisim lies, not some young Serbians that don't know better.
eg, a friend of mine from Spain used to call my black friend "Michael Jordan". For no other reason than the guy is black and Michael Jordan was the most famous black person he knew. Otherwise they got along great but there was a novelty and ignorance to it.