The world border red effect, affects the brightness of a mob's shader

The Bug:

The world border red effect, affects the brightness of a mob's shader.

Steps to Reproduce:

• Turn your graphics settings to Fabulous! (Options > Video Settings > Graphics: Fabulous!)

• Summon a mob with a shader right next to the world border. (Creeper)

• Enter spectator mode and spectate the entity.
  → ❌  Notice how when the entity moves further away from the edge of the world border, the brightness of the mob's shader changes. (The world border red effect is the cause of this).