For a long time now I have been using a textures on my characters ensuring the ScatterGroup is in different on adjacent materials.  I continued using the same figures after updating to 13.1.469 and the lines are back.

The fix for me is to make sure adjacent materials are now the same.  

I accept my skin texture is probably well out of date but I need some consistency for the story line I use the character for and do not want to update all my previous renders.  This present fix if fine for me but I did wonder about the change.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.