Lately I noticed on the Switch display something that you could describe as moving scanlines. When your eyes are fixed on the screen, you won't see them. They appear to show up when your eyes move or during movement in-game, not sure. Perhaps this is related to screen flickering or Pulse-Width Modulation. This is a technique devices use to dim the screen. If the dim frequency is too low, a human eye can notice that. I have no way to measure that so it's merely a guess.