It just say that they can be likened/compared to planets that are connected by the Dangai a tube it is confirmed directly in the databook by Toshiro and Urahara in MON
In this statement he talks about how the gathered souls inside Dangai connected both worlds.
Here you conveniently chose to forgot that Urahara explains how Dangai links both planets and why they can see cities from both planets
The diagrams show the Dangai linking both structures which is proof about both being planets as stated in the databook and movies
In the movie the konpaku turned into blanks and formed inside Dangai
Do you have an exemple ?
Yeah hence why I said Yhwatch wanted to destroy the planet to cause unbalance since he wants to destroy the air of that pitiful SS