I'm getting it too on a black Now Tv box. It's only on the right hand side of the screen for me. It looks like a textured pattern. Very strange. Bought a pass to watch the Man City/Man Utd game. Hope it sorts itself. All other channels are fine - clearly an issue with the channel/Now Tv rather than the devices.
watery picture several times Man city v Liverpool and other games including Man city v Wolves keep being told to reset nowtv stick which then takes 15 mins to reinstall all apps absolute ###### service only happens with sport.