Muffa substrato

Hi PeppeItalia, in my opinion, the mold formed more due to the lack of air circulation than humidity or temperature... I think you should check that your soil isn't too soggy, also put a small fan to help disperse the humidity. You can sprinkle the surface with natural fungicidal products like cinnamon, baking soda, or apple cider vinegar. These prevent mold from developing and won't harm the vegetation. Anyway, try using neem oil to keep the mold from coming back.

Definitely do turn air on. If there's only a little mold, you can try removing them with a knife, after which these spots should be treated with a copper sulfate solution. If that doesn't work, all substrate has to be replaced, the plant moved to another pot.