Is it the responsibility of the decorator or the property to fight the odor in the bathroom?

This still depends on the specific situation. I don't know where the deodorant in your bathroom comes from, but generally speaking, it is impossible to have no smell at all. Even if pretreatment such as U-bend and odor-proof floor drain is installed, it is impossible to ensure that there is no odor at all. Ask a professional to take a look at it for you, but it's usually because there is no deodorizing treatment in the early stage.