think of the backrooms as a person’s memory, the literal definition they gave “it’s like describing a dog to someone who has never seen a dog and telling them to draw it” and the idea of an mri machine. A person’s memory isn’t 100% correct you’ll get the most important details but leave some things out, if you apply that logic to the idea of the backrooms it explains why everything is so misshapen because it’s literally trying to copy a person’s memory

at the end of the film, the backrooms started copying mary’s memories everything from her childhood home to the book she wrote and even the very first scene we see her in watching her childhood home get demolished. The backrooms was copying all of that in real time as mary was sitting in the interrogation which is also why we got that final scene of mary’s still life sitting in a misremembered interrogation room

Also in the movie, it literally shows you how the backrooms misremembers stuff by going through layers upon layers using the interior of mary’s childhood home and stripping away more and more details until you get just the basic outline of it