In colloquial English, racism has the same meaning today that it did for decades before - a belief that humans' behavior depends on their race, and prejudice and/or discrimination stemming from such a belief.
The whole "prejudice + power" thing is a late social studies invention. Which is fine - different fields of study often have their own terminology, including using words in ways that do not directly match their regular meaning. What's not fine is people from those fields of study lecturing everyone else on how we're supposedly using it wrong. It's like biologists going around randomly yelling at people that tomatoes aren't vegetables whenever the subject comes up... except biologists don't do that.
The whole "prejudice + power" thing is a late social studies invention. Which is fine - different fields of study often have their own terminology, including using words in ways that do not directly match their regular meaning. What's not fine is people from those fields of study lecturing everyone else on how we're supposedly using it wrong. It's like biologists going around randomly yelling at people that tomatoes aren't vegetables whenever the subject comes up... except biologists don't do that.