I've had a verbal lease for over 8 years.
I have never had plumbing problems in this apartment. The owner, informed about the problem, suggests cleaning the hair strainer, but in my case the problem is more serious because the pipe is deeper clogged.
I live on the top floor. Only my wife and I have access to the bathroom. The initial problem appeared a few days ago - the drain from the bathroom sink was blocked. I cleaned the pipe under the sink, poured "Drano 10 min" several times and everything returned to normal. But three days later I saw that the water from the sink was pouring out of the bathtub because the main pipe was blocked. And at this point, pouring "Drano 10 min" again did not help. The pipe is so clogged that the water drains very, very slowly. I don't know what could have clogged the pipe. Certainly not hair, but it is difficult to throw something larger into a washbasin with a strainer or into a bathtub with a strainer. Therefore, I am surprised by what happened!