Even a bad boss is teaching something. Write down what they do so you know exactly what never to repeat.

Bad management is unpleasant and it is also unusually clear information. You are watching, up close, what happens to people when instructions are vague, when credit goes one direction, when someone is corrected in front of others. Most people forget those specifics by the time they are the one in charge.

Keep a short private list of what you watched and what it did to the room. Write the behavior, not the person. Later, when you have any authority at all, that list will be worth more than most advice you are given, because you felt it.