I'm just going to share an experience by saying that I have a younger brother (not namedropping anything) and I have regarded him in most of my life in a neutral-leaning-negative light, he's annoying sure, but he's not like really shit, or at least, I had until he started calling me a "black person", "blackie", and "monkey" (which I'm pretty sure is often compared with to black people in a really dehumanizing light) just to get a rise out of me, which first of all, is not accurate at all (I'm Asian), and second, it sounds like he was being genuinely racist against Africans just to piss me the hell off, "at the very least he isn't saying slurs" I thought to myself, months later, he recently started calling me the fucking N-word, really, really casually, just to piss me the fuck off, I don't know if he's being genuinely racist or just wanting to get a reaction out of me (I'm 75% sure it's the latter), but even then, using slurs just to get a reaction out of someone is tasteless at best, and outright derogatory at worst.
I'm just curious if anyone else has experienced the same thing as me.
Kids pick this stuff up from somewhere, try and find out where it is. If it is other kids at school, he's probably doing it to try and sound tough or cool, and will probably grow out of it (or get the shit beaten out of him for saying it to the wrong person and learn his lesson that way)
If he's getting it from online sources be extremely careful, he might be falling down a rather nasty fascist/incel rabbit hole there. I'm not sure what age he is, but a lot of fascists will court young, as young and impressionable as possible, so don't think "he's too young for that sort of thing." if he has unrestricted or unmonitored internet access he could've very easily picked this stuff up online.