In the accessibility section[1] they discuss the problem of using true black: OLED Smudge. If you turn off OLED pixels and the display suddenly needs to turn th

In the accessibility section[1] they discuss the problem of using true black: OLED Smudge. If you turn off OLED pixels and the display suddenly needs to turn them back on, they usually are too slow to do so, and cause a visual artefact that appears to the user as smudging up the screen—which can feel like the display itself is broken. This occurs on most OLED displays, including high end ones in devices like iPhone XS and Pixel 3, and is largely why true black interfaces should not be used. > "On OLED screens, turning pixels on and off can cause a delay when the screen is scrolled, making the pixels blur." [1] https://material.io/design/color/dark-theme.html#properties https://material.io/design/color/dark-theme.html#properties