Other than the metal side visible in the picture, were there any other visible materials for the door (wood for example)? If the metal is covering wood it becomes a conductor of heat and may cause combustion to occur in the living area of the home through conduction in the event of a fire in the garage.
What is the door frame made of? Even if the door were a labeled fire rated door, if the door frame is made of non fire resistive material, it has compromised the fire rating of the door assembly and basically nullified any fire resistive protection that the door would have provided.
Finally, any self-closing devices in the door assembly? Without self closing devices the door may be accidentally left open allow fire and the products of combustion (smoke, carbon monoxide, and so on) to migrate into the home unhampered.
IMO, if any of the above were observed I would write it as a safety concern where the door and its associated components may not provide for adequate protection from fire and the products of combustion. I would recommend repair or replacement with an appropriate fire rated door and door assembly.