Stop Hold up !! I know what is the problem
The only reason were getting that sort of "flicker" is because the page sort of goes a tiny bit into the left screen which is the spotlight page....therefore it thinks the page is away to get dark...but no it doesn't as it's pinged back to the normal first page (this only happens in like a millisecond)
If you sort of slide to the left a bit from the first page to the spotlight search you will see the screen sort of goes dark, let it go and it brightens up again
that could be the flicker everyone is thinking they have ????