Complaining isn't the behavior which makes someone a "Karen".
It's the manner in which the complaint is issued, and what the complaint is about.
If you (in a respectful, professional manner) complain about a genuinely rude CM or employee at any business, you are doing a favor for that business, future customers, and in many cases, the rude employee. Many times, a simple talking-to from their superior fixes the rudeness and makes them a better representative of that company moving forward. Had you never complained, you only enabled the rudeness or problem to continue.
If you complain in an angry, disrespectful, heated manner, or if it's about something extremely superficial not impacting customers or the business's image... that pushes you into the "Karen" territory.