They did also say in AFUtD that the Zone boundary isn't smooth and continuous, it's like a foam with ripples and bubbles near the boundary and moves around some

They did also say in AFUtD that the Zone boundary isn't smooth and continuous, it's like a foam with ripples and bubbles near the boundary and moves around some normally -- which is why ships that ply the Low Beyond near the Zone boundary always carry coldsleep units and ramscoops as a backup. Did we every get an in universe or author-commentary explanation confirming the theories about the On/Off? I always figured it was some high-tech artifact based on Beyond or Transcend tech that was going to remain mostly unexplained?