If a horse is wearing horse armor with the max_damage component set to any number and the damage_on_hurt tag from the equippable component set to true, the item doesn't take damage when the horse is hurt.

How to reproduce:

1. Execute the following command:

   /give @s minecraft:diamond_horse_armor[minecraft:equippable={allowed_entities:"minecraft:horse",slot:"body",model:"minecraft:diamond",equip_sound:"minecraft:item.armor.equip_diamond",damage_on_hurt:true},minecraft:max_damage=5]

2. Summon a horse and tame it.
3. Equip the horse armor you were given onto the horse.
4. Punch the horse.

Expected result:

Since equippable.damage_on_hurt is set to true, the horse armor would take damage when the horse wearing it is hurt.

Observed result:

The horse armor's durability does not deplete, despite the value of the equippable.damage_on_hurt tag.