Hello,
This is the expected behavior when you mistakenly took the green pill instead of the white
you should have think twice and now you are under the matrix trap 
well, to get out of the Matrix
I would suggest you try to Calibrate the sensor for that particular image resolution / FPS.
if you are not comfortable with this process, look into the manual, it is very easy and I think might be done on a routine.
noise on the sensor is sensitive to temperature, temperature changes, seasons changes, the space weather and the conditions in the matrix
Grin apart, yes I dont know why the calibration is unstable sometimes with the Chronos, but sh** happens, noise increase with sensor temperature, that is true, so when the sensor gets hot, I would say at working temperature, then do you sensor calibration for the particular FPS / resolution you are in.
you may start again a new calibration if temperature conditions change, like in hotter ambiant temperatures, or if temps. are really colder.
cold ambiant temp. will have only a slight influence on the camera sensor final temperature, I believe so, because as long as the sensor gets current, it simply heat up. and heat=noise in the camera sensor math.
Calibration will do many things on the sensor, vertical debanding, denoising with dark noise image substraction, etc. and at last will -hopefully- take you out of the Wrong MAtrix
Let us know how it goes, hopefully this is not something else.
Regards !
