LED lights at home not turning on sometimes
This might be a bit late, but about a month after I posted this question we found the problem. The issue was that the main circuit breaker in the hallway outside of my flat was faulty. We have a tree phase breaker there and the problem was only on one of the phases which meant everything was working mostly fine except the lights. Later I learned that the electricians used exactly the faulty phase for most lights in the house (seems to be a common thing to use one of the phases for lights apparently). After replacing the breaker all problems disappeared.