Light levels on blocks don't change at night

Cannot reproduce. Please provide more details (video settings, etc.)

Added screenshot of video settings.

What if you don't have Brightness set on "Bright"?

It returns to normal at 50% of Brightness. If I go back to Bright, however, it then looks like this.

For the appearance of blocks this works as intended. "Bright" video setting will make the blocks appear as if you had a Night Vision potion.

However, in the debug screen (F3) the sl (Sky Light) and rl (Real Light) values do not change from 15 when in open air, making it impossible to tell light values above ground. Refer to MC-9374 for a report on this aspect.

Except that when I adjusted it, it returned to the normal value of 'Bright'. The first image shows a 'fullbright' effect, which is the aforementioned bug.

That's not correct, Andrew. The Sky Light value is not supposed to change. That was kind of the whole point of the lighting re-write that occurred a couple of years ago, the Sky Light value determines how much of the sky light portion of the lightmap is used when drawing the block, and the Block Light value determines the same for the block light portion of the lightmap. The day/night cycle is rendered simply by changing the lightmap, not by actively updating the sky light value anymore. While I appreciate the input on the bug, it would be better for everyone if you gave accurate, relevant information to the discussion at hand.

Firstly, this issue was resolved ages ago.

Secondly, that is a duplicate of this one, considering it was submitted in Feb and this was submitted in Jan.