/damage fire can damage entities that are immune to fire

Almost all damage immunities work correctly with /damage. For example, frogs take 5 less damage when using the fall damage source, and cats are immune to it altogether.
This does not work for fire immunity. Entities with the fire_immune component or the fire resistance effect can still take fire-type damage from /damage.

How to reproduce

/summon cat
/damage @e[type=cat] 1 fall

It doesn't take any damage because it's immune

/summon blaze
/damage @e[type=blaze] 1 fire

It takes damage even though it's supposed to be immune. Same bug can be observed when targeting a mob with the fire resistance potion effect.