Stains in the loggia. What could that be?

Hello everyone,

I visited my parents yesterday and noticed stains in their loggia. They rarely go into the loggia since they have limited mobility.

They do not smoke.

The photo of the stains is attached.

What could this be? Could it be dangerous?

Could it be coming from the neighbor above?

The stains were definitely not there, for example, a year ago.

Thank you

Is it ventilated sufficiently? Almost looks like [Stockflecken]…

Is it ventilated sufficiently? It almost looks like mold stains…

Whether it is ventilated sufficiently… I am not sure if I understand the question correctly. This is a loggia and it is not glazed, so it is permanently ventilated in my understanding, like a balcony. Or is it about another type of ventilation?

Ok, I thought it was closed.

It should also be mentioned that the stains are mainly on the ceiling.