Items with the equippable component and the equip_on_interact field set to false can still be equipped to wolves, horses, llamas and alike on the body slot.

A given item with the equippable component and the fields equip_on_interact:0b, slot:body will still be equipped onto tamed wolves, horses, donkeys and mules (even if there’s no visible body slot in their inventory UIs) and (trader) llamas through the use button “right clicking”.

– Steps to Reproduce –

1. Get the item: /give @s minecraft:diamond[minecraft:equippable={slot:body,equip_on_interact:0b,can_be_sheared:1b,allowed_entities:[wolf,horse,donkey,mule,llama,trader_llama]},minecraft:item_name="test"]

2. Try equipping the item through the use button, “right clicking”, onto any of the mentioned tamed mobs: wolf, horse, donkey, mule, llama, trader llama.

– Expected Result –
The item does not equip, there’s no interaction animation and it stays in your inventory if in survival or adventure. (Like the behaviour of the saddle slot in general or the body slot in the happy ghast).

– Actual Result –
The item is equipped by the mob and it’s consumed from the player’s if in survival or adventure. You can /data get or just shear it to check if this is the case.