mold behind drywall near plumbing 53

https://atomic-wiki.win/index.php/The_Hidden_Problem_of_Mold_Behind_Drywall_Near_Plumbing

I noticed a musty smell in the bathroom, and when I finally cut into the drywall near the sink's plumbing, I found a patch of black mold spreading across the back side. It had clearly been growing for a while, fed by a slow leak from a pipe connection. The whole section felt damp and crumbly, and I'm worried about what else might be hidden behind the walls.