The landlord is obligated to carry out all necessary repairs to make the apartment habitable.
With one exception: the tenant has to take care of the repairs when the damage is not due to normal wear and tear and can be attributed to them, except if they can prove that the damage was not their fault or the fault of the people living in the apartment (art. 21 LAU).
To avoid surprises, it is important to document the condition of the apartment when you move in and when you move out.Therefore, take photos and videos of all the rooms both when you move in and when you move out.
If we want to be extra cautious, we can include a newspaper showing the date of that day in the video. This way, if there is any dispute, we can demonstrate the actual condition in which we left the apartment.