I believe this is the world or save failing to load something, and it kinda corrupts the world. I'm not entirely sure if that's the case, but I have seen this issue pop up before from others asking about the same problem.
Viewing post in Random or set event?
This is what I thought at first, I don't believe it actually is since I was rewatching and thought the actual reason I was sent to the """"backrooms"""" was because of the game placing back the objects around the base, and also the transition from the fog into this also makes me believe it could just be an event.
(edit, this was typed prior to seeing the posts below)