Had one happen to me recently where I was scrolling Spotify, and they do the thing where if you try to scroll past max they will stretch the content.

One of the album covers being stretched had some kind of fine pattern on it that caused a clearly visible shifting/flashing Moiré pattern as it was being stretched.

Wish I could remember what album cover it was now.

Though really it's simple enough: As long as you can still spot a single dark pixel in the middle of an illuminated white screen, the pixels could benefit from being smaller. (Edit: swapped black and white)

The single pixel example is wrong I think, because that’s not how light and eyes work - you can always spot a single point of light, regardless of how small - if it’s bright enough.

Yes exactly that's why I went back right away to edit - if the whole screen is white but one pixel is off and you can spot it, then my logic holds.