The silicone seal of the window has numerous unsightly deposits

I have also uploaded a picture, is possibly the masonry affected by it as well?

The paint on the textured wallpaper also has spores. You can permanently get rid of it with a Danklorix solution 1 to 5 Danklorix water. But from the sill rather not, that has to be removed and replaced. And then you should answer the questions of where it comes from. To stop it. K.

The color on the textured wallpaper also has spores. You can permanently remove it with a Danklorix solution diluted 1 to 5 with water. But not from the sill, that has to be removed and replaced. And then the questions should be answered where it comes from. To get rid of it. K.

Thank you very much, it is a plaster without textured wallpaper.