The bug

Wither/creeper armor is no longer affected by the fog from powder snow/lava.

How to reproduce

• Summon a powered creeper inside a large area of powder snow/lava

  /summon minecraft:creeper ~ ~ ~ {NoAI:1b,powered:1b}
  

  →  Notice how you can clearly see the creeper's armor

• Summon a wither with wither armor inside a large area of powder snow/lava

  /summon minecraft:wither ~ ~ ~ {NoAI:1b,Health:150f}

  →  Notice how you can clearly see the wither's armor

Note: This issue did not occur in 21w08b.