Dear Sami,
There are NO extreme high temperatures!
The camera is used in normal conditions, even low temperatures I would say.
Yesterday I tested it in my office, room temperature=22 deg. Celsius.
Today there are 15 deg. outside, cold and raining. The issue is still there.
It is the heat inside the camera the problem.
And I would not say the camera is overheating, it feels worm but not hot after 1 hour working.
For comparison, GoPro heat up when recording so after 1 hour you cannot keep your hand on it! That is heating! And still there is no change in picture quality.
In conclusion, the camera is heating normally but the optical and/or electronics inside are affected.
How did you tested this camera? You never let it run for more than 5 minutes?
I am sure the chinese people that bought this camera face these issues too, but I presume they are used to NOT complain about anything, wright?
and, BTW, is there a Novatek chipset inside, rebranded as Yi A12 ? Please be honest.