> "Asking to understand" is toxic and passive-aggressive.
It is the opposite of those things. The label applied to the approach isn't putting the words in your mouth. You don't lead with the question "I'm trying to understand why you did this. Why did you do that?"
You ask questions about the context of the situation. You listen, a lot. Then, when you have sufficient information, you decide how to act, whether it be a simple direct communication to that one person, or a this-is-who-we-are / this-is-how-we-do-things communication to the entire team.
Listening, the real technique under examination here, is the opposite of toxic. It shines light on behaviors, and helps a manager achieve the true goals of what would otherwise be a mere surface-correction. Listening is ameliorative. Asking questions, gently, and listening to the person is also not passive-aggressive. Giving the employee a bad review for uncorrected behavior is. Inquiry is one of a set of tools that any good manager should use. Not the only one, to be sure. It is not passive, it is directly aimed at increasing the situational awareness to best support a manager's judgement (maybe there's nothing here, maybe it is small/medium/large).
What kills work culture is allowing a problem to fester then blindsiding the person with bad reviews and termination. Explaining to someone early a) what the expectations are, b) how they are doing in relation to the expectations, and c) if correction is needed, how to correct and how to measure, leads to a much healthier work environment.