Mold on soil ?

Try spraying it with a hydrogen peroxide solution( I use a tablespoon of the drugstore type in a gallon of water), then back off on watering. Let soil dry out pretty well. If the h2o2 doesn't get it, There is a product called Serenade that is an anti-fungal. I haven't had to use it, but it was recommended by my hydro store. Also. if you haven't already, you may want to add some perlite to your soil next time to help aerate and drain soil. Good Luck🤟😜