When you switch between Fullscreen mode and windowed mode (like it's still kind of full screen but you can still X out of the application and stuff), there is a glitch where it will look black and white, kind of like the game is being electrocuted in a cartoon for like a split second.
(I understand that this is so small of a thing that there isn't really a point in reporting it, but it exists, so I will.)
Please provide some screenshots or videos of this issue occurring whilst the F3 debug screen is enabled.