While there are plenty of lovely people named Karen across different ethnicities, the name Karen has become the common shorthand for a specific brand of entitled white woman.
According to the internet, Karens are known for reprimanding and harassing customer service employees, causing scenes at restaurants, and at their worst - calling the cops on Black people who are minding their own business.
Most Karens are unable to realize they're a Karen unless they're already in the process of reforming and changing, which largely negates their Karenhood.
However, family members and close friends have an easier time spotting Karen behaviors, and it can be mortifying to be caught in public with someone prone to lashing out.
My Mom is a reformed Karen. When I was a kid she used to treat people in customer service like trash. When I was a teenager and in customer service positions, it finally dawned on her what a terrible human being she was being. She’s turned around and been great ever since. I’m proud of her to recognize her faults and fix them.