WHAT IS THE ISSUE?
When the player rotates their head, in some resource packs the second layer of the player's head does not move. It looks like the second layer welded to character's torso, with no hope of synchronized head movement along with its first layer.

HOW TO FIX THIS?
To fix this, we need to synchronize the rotations of the 1st and 2nd layers of the head, so that the second layer would not be a part of the whole body. Secondly, we should adjust the position of the second layer to all helmets in game. Thirdly, subjoin the support for special character models.

WHICH RESOURCE-PACKS DOES IT AFFECT?
BlockPixel by Jakob_zero (@RainbowPixel);
City by Minecraft (@4JStudios).