Please stop with these incorrect generalizations. Hush agreements are definitely allowed in Germany as well, part of golden parachutes usually.

I know a manager at a big auto company who also had to sign one when he was let go and was compensated handsomely to keep quiet on the technical aspects he learned and the incompetence of the company leadership he witnessed, and not say a word or face legal consequences.

IIRC he got ~12 months wages. After a year of not doing anything at work anyway. Bought a house in the south with it. Good gig.