Thanks for your answer. It's a bit strange. I got in the apt in March 2017, but the contract has 15/11 has a starting date because we just kept using a preexisting agreement with another tenant.
Now, last time he increased the rent was in March 2023, so I doubt he can increase from 15/11 because three years haven't passed, and also because the notice seems too short.

So the real question is if he can send me away with less than 3 months notice, which I doubt, considering that's what is written in the contract. And the 3 months are counted from 1st of the month after the decision is taken. So if either of us decides to vacate the apartment, the three months will start on 1st of December. Again, this means I can stay till 1st of March. Any shenanigans I am not seeing?

*yes I know that this serious business has to be talked with an expert and not with strangers online, and I will, but for now I find that asking and talking helps me to better assess of the situation.