How do I keep mold away from the attic?

I believe that our attic is inside the thermal envelope. It is super insulated. For now, I have fully opened the floor hatch and tilted all the windows on the upper floor. Due to wallpapering and painting, there was more moisture in the house again. I treated the mold stains with spray. Now at least it only smells like chlorine and no longer musty. Somehow I have the feeling that the climate in the attic is better when the floor hatch/staircase is open as much as possible. Maybe the moisture in the attic can only be permanently removed once the painting work is finished.

In our case, the actual thermal envelope is the ground floor with an insulated ceiling. The floor is outside, but was completely uninsulated as a cellar replacement and only usable to a limited extent, as it was too cold or too hot, and also too humid in winter. Therefore, it was subsequently insulated in the EL. The Velux for ventilation and daylight is worth its weight in gold.