In singleplayer and also on various multiplayer servers, on an open field (e.g. grass), the light level still remains at 15 in the night. Just walking trough trees decreases the level.
Important: The light level SKY remains at 15, not block.
MC-94980
Light Level always 15, even at night
Resolved
Duplicate
0
Intentional.
Light(Block) is what is used for mob spawning.
Light(Sky) is used for mushrooms. That's why you can't place them at night without blocking the sky.