The bug
When you put a light under the water, it acts as if smooth lighting is off. I tested all the light sources that can be underwater and all had the same effect.
Same happens with night vision effect.
This can best be seen when setting Brightness to "Moody" in video settings.
Linked issues
relates to 2
Attachments
Comments 36
Confirmed in 1.8.3, best visible on a light underground, see screenshots with Respiration III and Night vision
Still not happening to me. I see a very visible difference between the two settings. See attached screenshots.
There is a difference between smooth lighting off and max, but event at max setting it's not smooth as outside of the water.
What? I wasn't expecting that bug to be ever fixed. But I understand why, if it didn't affect a newly added thing (MC-205840), Mojang wouldn't fix it and it would take even longer to be fixed.
@unknown, your screenshot shows that smooth lighting doesn't work on the surface of the water, and that is currently being tracked in MC-227302.
Fry
Can't confirm in 1.8.3. Looking at your screenshots, you don't seem to actually be having the problem you are describing. That lighting is perfectly smooth.