The cushion is literally located behind the texture, and you can even sit on it. Visually it cannot be seen unless you turn on hitboxes. I think, this is anyway bug, even if you can't use it for personal gain.
This is a highly exploitable bug. Players can easily use this glitch to bypass solid walls or ceilings, completely breaking base security and map boundaries. I highly recommend addressing this issue as soon as possible before the final release.
Okay, thank you for answer!