Yes.
To be racist is to attribute negative or undesirable characteristics to someone based on the premises of their race and their race solely.
I've seen some ATRLers make ignorant comments about white people which baffles me because if the roles were reversed there would be a huge uproar
Sure, calling me a thin-lipped cracker won't stop be from getting a job (which is cute because I'm neither thin-lipped nor a "cracker") but you unknowingly create a racial barrier by saying damaging things.
Why do you think straight, cis, hetero men are so reluctant to support gays, women, etc. ? Why do you think terms like "FemiNazi" get coined? When the minority begins perpetuating hurtful, inaccurate stereotypes you make the majority reluctant to be supportive.
POC CAN be racist and it can be just as damaging because you widen the gap between races, thus making the end goal of total equality further away. To achieve equality we need to bring ourselves up - not tear others down.