Article reference KA-02386
The glass cloth will deteriorate and this is normal. This material does not contribute to the thermal performance of the insulation. As long as the microporous material is not damaged or crumbling then the insulation performance will not be impacted and it will be safe to use.
ie; Below is an example where the microporous material has started to crumble, and in this example the door insulation should be replaced if disturbed:
Applicable Model
QM – QM050, QM070, QM100, QM125, QM150
QMRF – QM050RF, QM070RF, QM100RF, QM125RF, QM150RF