I wasn't even testing anything here, just getting all the endings. Basically went through a door (the one leading into the Pyramid Head chase sequence at the end of the Hospital with Maria) and was loaded OOB. I then soft reset the game to start a new game for the next ending, every single save had the same room corruption to the point where I had to actually restart the game fully. From what I can tell, this can happen randomly, and it seems to be quite useless anyway because the room that loads AFTER the current room, seems to have no hitboxes.

Had this randomly happen yet again but this time in the room where you pickup the flashlight, So that and the Hospital Basement with Pyramid Head is two places it is known to happen although I'm wondering if it can just randomly happen anywhere. PS. This is the Japanese "HD EDITION" version, so it's happened on both US and JP versions at this point (fully updated).