Several Smooth brushes are available in all the smooth brushes. Using Smooth at different subdivision the currently-selected Smooth brush, hold a high subdivision level whereas your model is affected.
Your selection will then become active every time you hold down the Shift key, until you select a different Smooth brush. I think I found the problem, when I turn on polyframe, it shows an uneven spread of blocks, and they get really big right at that line. A new Smoothing Algorithm The Smooth brush includes an alternative algorithm, added to create a better result on the poles of the topology of the model when a vertex shares 3, 5, 7, etc edges.
