mold behind drywall near plumbing 16

https://getmoldremediationstlouislife.solsticebrief.com/posts/hidden-mold-behind-drywall-a-st.-louis-rental-home-case-study

There's a musty smell in the bathroom that I can't get rid of, and I finally found the cause after pulling off a loose piece of baseboard—there's mold growing behind the drywall right where the plumbing runs. The previous owners must have had a slow leak for months, because the paper facing is dark and spotted behind the wall. It's not visible from the outside yet, but the texture of the drywall feels damp and crumbly.