I don't know if this is already known to be "WaI":

The bug

If you're in Spectator Mode and go only a bit into a solid block (on "feet level" already), the Sky darkens. I can understand this behaviour if you're completely inside solid blocks, but I wonder if this really should also be the case for when you're only a tiny bit inside a block?

Steps to reproduce

> Go into Spectator Mode, go to ocean level Y=63, teleport yourself to ~ 62.95 ~ and see the sky darken.
> Y=63.0

Expected

I'd have expected that the Sky darkens as soon as you're inside a block on your eye level.
I'd have expected to not be the case on feet level already.

(I don't consider this a suggestion/request, but an illogical inconsistency of sorts, but if you do consider this bugpost invalid, I'll live with it )

It was fixed for me in 1.12 pre-2 (see my comment below), the Sky gotten only a slight darker tint, but it's again happening in 1.12.2 release, so whatever changed inbetween these versions seem to have affected a fix for this bug.

2017/10/26: In 17w43b it is fixed again (didn't test 17w43a), but given the fact that it already was fixed once before and then occurred afterwards again, I suggest to leave this bugpost open until 1.13 release, but the decision is of course up to the mods, I can also just have it being reopened again

Update 18w01a: Still slightly darker, still better than it was in the very beginning, but still unsure whether the current optical status quo is WaI or not.