As per net.minecraft.entity.monster.Entity'mob'.initEntityAI(), a mob's entityCallsForHelp boolean in the net.minecraft.entity.ai.EntityAIHurtByTarget class is always set to true, which means that it will alert other entities within its followRange as soon as it gets attacked. However, if the player dies, this code will not be initialized. Therefore, mobs cannot alerts their fellow mobs.

• The following mobs are known to be affected:
  Evokers, Pillagers, Vindicators, Illusioners, Ravagers,
  Zombies, Drowned, Husks, Zombie Villagers
  silverfish, endermite, vex

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