You are correct that there are multiple somewhat-conflicting definitions of racism but “taking past each other” isn’t really what’s happening.

The “classic” definition of racism is something like “a system of oppression based on race”. People pull that out to explain why “[minority] people can’t be racist”, but that that definition isn’t about people. It’s about systems, so if we take that definition, no individual can be racist. Most of the same people who trot out this definition will still call majority-race individuals racist (clearly using a different definition). It’s a rhetorical sleight of hand to swap definitions in a self serving way like this.

> racism = prejudice + power

This seems like an oversimplified perversion of the “systemic” definition and doesn’t make sense if you actually consider it. By this definition a poor white woman basically couldn’t be racist, while a rich black man could.