Is TV getting lighter and darker?

For a couple of weeks I have noticed when I'm playing or looking at something on my Ps4 that the picture gets lighter and darker every now and then. So the graphics are still fine and you can see everything, but you just notice it. Has anyone ever had that and knows what might be the cause?

Does your TV have an "intelligent sensor" like your cell phone?
Then he likes to widen with certain energy-saving settings