Boss bar dims screen in multi player

in Multiplayer when there is a boss with a health bar, when the health bar becomes visible. The screen darkens slightly.

the mob is an invisible wither with blindness, slowness, and weakness with no AI, its persistent, and its silent. it has 20 HP 999 knock resistance, and is named Infinicraft!!! also it is most viewable at night but slightly affects the sky during the day

command to summon:

/summon WitherBoss ~0 ~1 ~0 {CustomName:Infinicraft!!!,CustomNameVisible:1,Attributes:[

{Name:generic.maxHealth,Base:20}

,

{Name:generic.attackDamage,Base:0}

,

{Name:generic.followRange,Base:0}

,

{Name:generic.knockbackResistance,Base:999}

],ActiveEffects:[

{Id:15,Amplifier:1,Duration:999999}

,

{Id:14,Amplifier:1,Duration:999999}

,

{Id:2,Amplifier:1,Duration:999999}

,

{Id:18,Amplifier:1,Duration:999999}

],NoAI:1,Silent:1,PersistenceRequired:1}

also, It only works in multiplayer. Single player is free of this bug

I'm not sure if this is intentional to add affect or if its just a bug, but its annoying none the less

thank you!
Jackson_Cat