I was living there during the Berlin city governments (failed eventually) attempt to control rent by just regulating it down - they assigned an actual value to

I was living there during the Berlin city governments (failed eventually) attempt to control rent by just regulating it down - they assigned an actual value to each apartment, and mandated that was the new rent. Naturally, the estate agencies took them to court over the extremely debatable constitutionality of this. We kept paying our old (not revised) rent based on some legal advice while the court case went on. The difference was close to a thousand euros per month (dramatically overvalued tiny, old apartment) People who switched to the lower rent, ended up being forced to make back payments, which financially crippled a lot of people I knew there. This happened alongside corona, so it wasn't like people could just easily hold on to money.