In what way is failing to see humanity in a group of people based on their skin colour, not racist?

Apparently it’s OK because it’s white people though.

I’m not saying you’re wrong to call out racism (you’re right to be frustrated and upset) but to go and dehumanise an entire group of people based on the actions of a few, in what crazy world is that NOT racist? Just because you consider it justified racism doesn’t make it not racist.