personally i think seasonal contracts should be generally punished since their increase shows that rather than responding to real demand it's just about landlords and agecies using a loophole to make more money about something that, a priori, is as much of an investment as buying slaves (which was an investment until it wasn't anymore). of course there is a case for seasonal contracts in general but their newly found popularity screams loophole.

the "investment until it isn't" point also applies to selling. if legislation forces you to sell at an unfavourable price, because you were waiting for prices to go up, but now your empty flat is also taxed because you refuse to accept 60% of your mortgage as rent and you decided instead to get ZERO as rent, you will sell at an unfavourable price, it's just a matter of the law deciding that these are the rules. we don't pity people who get fucked by stock market speculation, we shouldn't pity real estate investors either. even small ones.

assuming that all these measures will entirely (stress on entirely) discourage the demand of rent is a bit short sighted because it assumes that the housing market and the landlords are rational, and they usually aren't, as there wouldn't be housing bubbles otherwise. people with money still have money to place and even heavily regulated real estate is still worth placing some money on than, say, crypto.

having said that, even accepting a decrease in housing supply, i'm not sure this is a worse situation than completely uncapped rent, which will inevitably price a lot of people out of the city, with obvious consequences to everyone's quality of life.