When putting /effect give @p minecraft:night_vision 1 1 true in an always active command block will causes a rapid flickering effect (which is because of the visual that occurs when your night vision is about to run out) that is prominently visible at nighttime.

While the flickering was way worse before when doing the same command, the flickering still exists, albeit to a lesser extent.

(Seizure Warning for video) https://youtu.be/rmFUowa0iDE