Shulker heads do not flash red when taking damage / when killed

Despite the fix of MC-218695, only the head of the shulker does not flash red when taking damage or when killed.

To reproduce

1. /summon minecraft:shulker ~ ~ ~ {NoAI:1,Peek:100b}

2. Hit it once
   ❌ The shell of the mob flashes red but for its head.