Well that's very disappointing.
What about the thriving culture which exists in Berlin, and which is supported by low rent prices.
For those downvoting - look at literally any city that has implemented rent caps and tell me that they are a good idea. Where the standard became asking for 6 months upfront and signing a 3-year-no-exit-clause contracts because the demand is so huge it allows landlords to do that. Is that really a net benefit to people renting?
On the other hand, if rent controls are used as part of a wider strategy to gradually convert private rental stock over to social housing - that is, as a stick to encourage private landlords to sell up to the public sector - along with other measures including more state investment in building such housing, large fines for private landlords leaving their rental properties unoccupied, and so on, then this can be a long-term positive on the overall housing situation.
The end goal should be to remove this wholly unnecessary parasitic landlord class from the housing provision entirely, rather than tinkering around the edges of the problem, as this Berlin measure was doing.