Qidi cost saving again it sounds like. It was the same for the X-Max, the earlier versions were much more robust with an 8 mm alumimium bed like mine then they switched for a 6 mm bed, there were also more steel sheets in the enclosure.
I was not aware they changed the rod size though. If I get the bearing specs and distance between the rods I can make a version for 8 mm rods pretty easily.