The Backrooms have always reminded me of House of Leaves and the Navidson Record within specifically. (I think maybe that's a deliberate influence in the lore?)

So I like how the movie's plot seems to be similar as well.

I think there's a bit of a convergent evolution

House Of Leaves is similiar to Backrooms in a way - they represent the same kinds of horror but it's more like how Weird Fiction converged and inspired in the same way. There's a level of early slenderman there as well (in terms of a lot of the early slenderman horror being more about the horror of dreaming this entity into the real)

I'd argue SCP Foundation is probably one of the main initial examples of internet occult, the Backrooms have more in common with a few SCPs.

To go wider there's probably a convergent horror - It's the classic aspect of horror stories of the age represent subliminal fears of the age (e.g, bloodsucking vampires mean very different things across the past thousand years). I think liminal horror is a representation of a lot of our fears, so multiple different effective horrors have converged on these feelings of discomfort with spaces.

I'm not really smart enough to know what it means - probably something about modern society dissassociating people from the space, but don't know much more.

I was thinking of House of Leaves reading the other comments here, mostly because something like an infinitely long tunnel to nowhere hidden in the walls of your house would actually be scary to me, whereas normally occupied spaces being empty and long winding indoor hallways are far more mundane. My wife has gotten into backrooms lore quite a bit in the past few years and it's always struck me as a strange thing to find eery. I've been an early morning runner for much of my life, worked overnight shifts at a theme park, closing at a mall, been in the tunnels beneath Disneyland and downtown Dallas. Worked in stores that hadn't opened yet and had nothing in them. There was nothing scary or eery about any of those things. It seems like an effect of the photographs and presentation more than the reality of the physical places. House of Leaves is scary specifically because it can't be real. Another example is something like the wormhole to 1987 and 1954 at the end of a cave in Dark. Yeah, that's scary, because nothing like that exists and you have no idea what to expect going into it.

Ironically enough, I first read this book when I worked at Disneyland, at an attraction with tunnel access, that no longer exists, and I no longer have the book because I loaned it to a girl I worked with there who never gave it back. She and I hung out in those tunnels during breaks.

Also interesting to me seeing other responses about found footage, given the guy who first recommended this book to me was a friend from college who covered his dorm room in bizarre free-form prose that switched between play style and novel style during a manic episode, then tore it all down later, set it on fire, and pieced together what survived as the strangest pseudo-poetry that somehow still had a lot of real words in it, kind of nature's "found poem." This book was probably written around the same time Blair Witch Project first came out and this guy also lived next to the real Greenway Trail in Burkittsville, which was also not particularly scary to see in person. I kind of doubt that was really the first example of a found footage film but it's the first I'm aware of. Wikipedia is saying The Connection from 1961 is the first.