If you go in spectator mode, and spectate a creeper, you will see how the creeper sees the world. But if you goes and spectate a mob with nigth vision, you will note that the nigth vision effect is no displayed in screen unless you have the same effect

How to reproduce:
1.- Open a new creative world with cheats enbleds in minecraft 21w13a
2.- Take a nigth vision potion and throw it to any mob
3.- Then put youtself in spectator mode and spectate the mob with nigth vision
4.- And you will see the problem