Final resolution – camera back from repair. Fixed as replacement camera. My new camera does not exhibit the dark frame calibration issue. Now, when I create a master dark from a set of single dark frames and then subtract this master dark from any of the single darks and do a STF_Max stretch in PixInsight, I can no longer spot the remaining amp-glow! At the same time, I have tested two new ZWO ASI1600MM that I ordered for my friends, and both these cameras were OK with regard to dark frame calibration and amp-glow removal. Heureka. Now I need to decide if I keep the QHY163M or just replace it by something else that will not have QHY in name. I decided to sell all QHY items that I ever had and never want more to own their products – I have said this already two times in the past so for now – for the 3rd time – never more QHY (at this time I am more than happy with the „red Chinese camera maker“ ZWO).
Up to now, I replaced my spare (for the case) QHY5III-178m (blue) for a ZWO ASI290mm (red) to in-line all my equipment for ZWO (red) and Moravian (black) brands.