Damage_resistant components prevent an item from taking damage after coming into contact with a damage type tag, either when in item entity form or when equipped. This can be seen with it's basis in Netherite items and armor, which do not take damage nor can be destroyed by any blocks or attacks under the #is_fire damage tag.
However, this does not equally apply to shields and wolf armor. Currently, while these items will survive it in item form, they still take damage after blocking a certain damage source (holding right click with the shield and passively with wolf_armor) when equipped or used, even with given the damage_resistant component to match the damage tag.

Steps to Reproduce:
1. Open a world

2. Give yourself either a shield or a wolf_armor with a damage_resistant component set to #is_fire. Example:

/give @s minecraft:shield[damage_resistant={types:"#minecraft:is_fire"}] 1

3. With a shield, hold up the shield to block the damage from a fire charge shot through a dispenser. With wolf armor, have it be worn by the wolf and have them recieve a fireball from a dispenser.

4. Observe what happens after the fireball is fired and hits, and check the item's durability

Expected Result:

• The shield and wolf_armor took no damage from blocking the fireball.

Actual Result:

• The shield and wolf_armor received some durability damage after being hit with the fireball.