Thermometer

[micheus]

In first render its sun with default setting. (and yes its real)

Maybe because of that.
As I see a indoor floor with a strong light "entering" across a supposed window or door I expected to see a darker shadow in the opposite side of the object "touched" by the light.
But, observing better the lighting the "glow" upper in the image suggest you were not using a enclosed environment (room), so the "white" sky seems to be illuminating more the scene as I would to expect (thinking in a enclosed scene).