If there is a decal on a part within a humanoid, that humanoid’s shadows will envelop the whole decal. In the video below, I insert a Humanoid into the part – after this, you can see the decal become much darker because of the humanoid shadow. You can also see in the corner that this shadow is disrupted by my own character’s shadow.
This isn’t noticeable on character faces because a part named “Head” with a SpecialMesh is a special case not affected by the bug. Naming the part anything other than “Head” (such as “Torso”) or not adding a SpecialMesh to the part will result in the bug occurring.
