These discolorations are fluff that has remained stuck in the stitching seams.
You should know, first of all, that this is not harmful to your baby. The fluff is fixed and the effectiveness of your AeroSleep is not affected in any way.
In order to prevent this fluff or to remove it, we advise as follows:
Always fold your AeroSleep with the honeycomb structure on the outside when washing at 60°C and put it in the washing machine like this. Preferably do not add any other laundry.
Vacuum the AeroSleep. This will release most of the fluff that will then be vacuumed up.