ironically very underrated topic, even jf it seems like a meme coming from jp. Molds make a cocktail of secondary metabolites, and just the spores themselves are a problem. We have no idea how damaging it is but ive looked into a couple of the most common mold species and they all produce certain mycoestrogens.
I remember years ago hearing many stories of how the main benefit people going off grid into nature get is detox from molds in their original apartment, usually after being chronically sick and trying everything else
It could be hidden in places you dont know to check, like in your walls, washing machine piping, behind furniture etc.
its not just le black corner of bathroom wall