i can confirm that, the first few lines of the screen can have weird color
marks on them if you are using alot of other sprites while still having most
of them up in the corner

> switching off the sprites by filling the OAM with zeros does _NOT_
> switch off the sprites. instead it places all sprites in the top left
> corner of the screen - these sprites are invisible but they do very
> well steal cycles from the rendering circuit, you will get funny
> errors when you try to display a bunch of visible sprites in the same
> Y area.