Not a typical symptom of healthy medium.
I do coco and pasteurize the medium before potting,
so I don't have direct experience to the symptoms your pots show.
In my humble opinion, I would prep new coco and take cuttings
of keeper plants and at least sterilize the grow room.
Employ bleach or at least some H202 in recommended dosage to the
medium of the plants you have.
Good luck.
Maybe use a bacterial Myco product for best results. Sterile grow mediums are perfect for fungus
and mold to grow as they don't have bacterial competition. I like Plant Success Great White and
need to order again. I just ordered another Myco product called Photosynthetic Plus a few days ago.
I have 3% h2o2 how much to add lets say per litter or gallon to sterilized completely?