Karen is a pejorative term for a white woman perceived as entitled or demanding beyond the scope of what is normal [1] so it is just as "racist" as many other "racist" things. If "Karen" isn't racist then neither are many - if not most - things which are deemed racist. I'm fine with that so I hope you're sincere and are willing to follow this old-new definition of racism. If the term goes back to where it belongs - the assumption of people's traits based on their physical appearance with a heavy emphasis on skin tone - and it ceases to be bandied around as a label for anything which happens to displease the one doing the labelling the world will become a better place.

[1] https://en.wikipedia.org/wiki/Karen_(slang)