On this bonsai Ficus natalensis the lowest branch on the right side is not thick enough. Most often the lowest branch should be the thickest on the tree. In order to achieve proper thickness the branch is allowed to grow longer than the style dictates. Note the leaves are also larger than the rest of the tree which is being trimmed regularly.
In a year or two the branch will thicken because of its continued growth and then it will be appropriately shortened. The next step will be to continue the process of shaping the branch properly.