YES that is clearly the ladder on lu guang's side, not the upper bunk railing. it's on a diff side, and he's lying inside of it, so it's definitely the lower bunk. and the way the window appears behind cxs is only possible from the lower bunk too
THEY'RE SHARING THAT SMALL BED
LIKE they were always seen at least on the same platform/side by side, but starting from yingdu arc they were standing on different platforms. And now on S3, they seemed to walk on different path and directions