As far as I remember from Snapshot videos the lighting isn't what it should be for me, I noticed it more when I actually saw an ender rod making the bug, as seen on the attached screenshots (Red circles). However after a while (think about 5 min. or after doing something specific, I wouldn't know) it restores itself for a small part (White arrow)

NOTE: for now this bug is only seen for me in the 'End'

My settings have smooth lighting and 20+ brightness, however, changing them doesn't seem to affect anything.

Thought I needed to share this,
Spike.