As someone observed in the Twitter thread, +64% only means a handful (about 150) new flats on the market, since there's so few at the moment. They are now on offer for long term rental, so once they'll be taken they'll be out of the market possibly for years.

This is why comparing long term rentals and airbnb makes little sense: yes, half of the flats for rent at any given moment are for short term. But they're always the same ones, over and over again. They could increase the long term offer only for a few days before disappearing for good.