ᐅ Mold on drywall—only surface level?

So, we now have every builder’s nightmare: mold.
At the moment, it’s only on the drywall and only in the corners where it meets the (still) damp interior plaster.
Some areas are already quite large, black, and fuzzy.
We are not going to ignore the mold spots.
I have read that in 90% of cases, moldy drywall should be replaced entirely rather than just treated with mold spray. This is mainly because drywall is a very mold-friendly material, allowing mold to grow beneath the surface as well.
We will try to have the walls replaced (we also have an expert assessment), but just to ease my conscience, I’d like to know: if the mold has only been there for a few days, is it possible that it is truly only on the surface, or could the problem have been developing beneath the surface before it became visible?

Thanks in advance for your answers!

Hello 🙂 How did it turn out for you? We just discovered the same problem today and are feeling a bit desperate. Good luck

After the interior plaster, we noticed very slight stains... wiped off mold several times thoroughly, and the problem disappeared or at least nothing new has appeared since May in our case.

How bad is it for you?

So if it's about the period after the screed installation when it is really humid, I can probably reassure you. I also got worried when I saw black spots on the drywall. It looked really bad, but it was ultimately just a buildup of construction dust that, due to the texture, looked like mold. This happened in areas where some condensation had gathered. Mold does not just start growing overnight...