The player texture gets very dark after stand next to the following object:
Door
Torch
Fence
Fence Gate
Trapdoor
Vine
Ladder
Glass
Iron Bar
Double Tall Grass/Flower
Spider Web
P/S: This can happen to mob too, 2 blocks or 1 block tall. Still, I have not tested it.
Duplicate of MCPE-8392. Please comment any experience there, and vote for the issue there if you want it fixed sooner than other bugs.