Is it okay to insulate a WC wall with leftover glass wool?

Hello,

we are currently starting the renovation of our bathrooms.
Our toilet is located in front of an exterior wall, which is insulated with 160mm insulation from the outside.
Inside, the craftsman has now clad the substructure with drywall, and I noticed that he stuffed the cavity with remnants of fiberglass insulation.

Now I am wondering, besides the advantages like soundproofing or additional thermal insulation, whether this might actually be an unnecessary risk regarding mold/moisture?
Could it not be that moisture enters the cavity and the fiberglass insulation starts absorbing it and developing mold?

For the wool inside the 160mm insulation to mold, it must be quite cold. Filling the cavities is sensible to avoid large sound chambers - especially in toilets. This makes the flushing significantly quieter. Additionally, the wool prevents condensation on the outside of the flush tank (i.e., outside the container - behind the drywall). Mold problems are not to be expected there, as the whole thing is sealed and located inside the wall in front of the actual insulation layer.