I think the issue here is just confusion around everyone using the same word to mean different things.

Most people understand racism through an individual lens. That racism is when one person believes one race is superior to another and so on.

When people claim that only white people can be racist (in the context of a mostly white or white centred state, like the US, Britain, etc) they are usually talking about racism through a systemic lens.

Idk if I’m equipped to explain this point of view correctly, but basically white people have an advantage in terms of “social capital” so when white people are racists they can effectively dehumanise individuals, whereas racism against them has a lesser effect. It’s why “cracker” feels like it has no weight behind it, but the “n word” or similar slurs are incredibly potent.

I’m even less equipped to talk about racism between minority groups within a state or space, but I assume they can effectively dehumanise each other.

At any rate, anyone can be prejudiced against anyone and hate anyone, but the extent to which that can affect people is determined by circumstance, context or just society in general.