Getting weird mesh in mixamo

Hi all,

      I created fatty humanoid & uploaded in mixamo for Auto Rig bt in Mixamo the mesh is looking weired at the waist. I tried many ways like increasing vertices at that part, adjusting bones after mixamo downloaded file, increasing & decreasing of height, width, legs & hands mesh adjusted bt no use the same result is coming like folding waist can you plz fix this issue. Thank you