It seems like there was a new firmware and app version deployed.
I have to test if the issues are gone now completely but it seems that the artifacts issue in photos and videos is now gone and back at the quality level before the 1.6.3 version and without the other bugs. I will have some tests these days and report here.
UPDATE: ok the quality issues really seem like to be history BUT…
… right now you have to deal with constant WIFI disconnects. It´s like a nightmare what´s happening to this perfect hardware on software side. with every software update one issue is gone but a new is popping up.