This happens in Germany.
Work culture doesn’t fit my personality: I don’t talk much, I keep to myself, I simply want to do my job and go home, I separate my personal life from work, my colleagues are full fledged gossips, ignore the duties that need to be done and then expect me to help them when they are late. I don’t have patience for that crap anymore.
Due to internal regulations, I have to stay on the unit for 4 weeks after sending my notice. Answering honestly the question of why I’m quitting would ensure that they yell at me and bully me, and I don’t want to experience that again. Even saying ‘it’s none of your business’ ensures that they feel insulted and start yelling. I have decided I don’t have patience for people like that anymore.
So, what do I say?
Say something like:
“It’s best not to discuss such details at this time”
Which will tell them, yes, there is a good reason, no, I can’t tell you since I don’t trust you.
You will never get in trouble for something like that since you literately are not saying anything.
The bonus part is that if the coworker is cool, they can just reach out to you a week or two after you left and you can be honest if you think they are worth it.