If you want something completely FUBAR, you can always trust your local German bureaucrats to do a good job at it, especially in Berlin.

I wonder why they haven't tried increasing building supply and limiting external illegal immigration first? Also, why haven't they tried preventing these tax dodging stock market listed real estate mega conglomerates from owing a large proportion of the housing stock, as for them it's an investment for rent seeking that must make a return for their shareholders, rather than just shelter for someone. Crazy that Germans/Berliners let this happened yet see no issue with this and instead though that artificially capping rents was somehow magically gonna fix this. I guess most citizens don't really grasp the function of the housing market or the economics of it and instead will just vote for a quick handout. "Give them bread and games."