Yep it's a known issue that's been reported to the devs.
1. There's a weird box shape on the butt
2. There's a large crease on the hips between the butt and the hamstring
Folks have supposedly figured it out- the front and back leg textures were reversed in the latest patch. If so it seems like a simple fix so we'll see how quickly they can revert this as I and many others love looking at their toon's rear.