When I worked hospitality, a Karen was someone who automatically assumed that anything not exactly how they wanted it was a personal slight, that you as an employee are not important enough to fix it for them, and that anything short of grovelling is grounds for being fired.
If they listened to you explain why something occurred or why it was the way it was, not a Karen. If they didn't threaten to escalate because you weren't offering enough compensation, not a Karen. If they didn't blame you personally, not a Karen.
And, funny enough, most Karen's I've encountered were men in their mid 40s