Dim and yellow screen on a Lenovo Yoga HD+

The brightness settings on my Lenovo Yoga HD+ seem to change at random. I have checked the settings, and I made sure to select full brightness and deselect the automatic adjustments. This made no difference. What worries me a bit is that when the brightness goes down, the entire screen becomes also more yellow. If I go back to settings and change the brightness manually, everything goes back to normal. What could be the problem?
