(Visual inventory) banners with NBT tag but no pattern clone the pattern of banner to the left in inventory row

If a banner is broken by the player, it gets an NBT tag, even if it doesn't have a pattern on it. Then, if this "Null-NBT" banner is placed to the right of another banner in the inventory, it will assume the NBT data of the banner nearest it on the left. However, this "null-NBT" banner will not actually have the same NBT data as the banner on its left; it is only visual.