When to Remove Moldy Carpet and Padding Instead of Cleaning
https://mildewwatch.vantagequill.com/posts/when-to-remove-moldy-carpet-and-padding-instead-of-cleaning
If moisture has soaked through the carpet and into the padding, or if the mold covers a large area (over a few square feet), it's usually best to remove both layers. Even after deep cleaning, mold can linger in the padding or the carpet backing, where it's hard to fully kill. This hidden growth might keep releasing spores and causing musty smells or health issues. Once you see mold spreading or smell that telltale odor, replacing the carpet and padding is the wiser, safer call.