If base armor without a smithing template on it is placed in an inventory slot where there was previously smithed armor, the inventory sprite of the gear will change to appear to have been smithed using that template. If put on, it does not have the design. (the same thing happens to the sprite if the gear is put in the armor slot, as seen with the gold chestplate in the image. My netherite chestplate was previously occupying that slot.)
This issue is being tracked at MCPE-187679.