An image of the room in a model editor: flo1.jpg
An image of the room in Firefly: flo2.jpg
As you can see, the middle of the floor is divided a bit. The middle isn't raised or set at a different angle from the rest of the floor. However, it seems to be lit more brightly in Firefly.
Why is it does it look so bright in contrast to the rest of the floor? It's very irritating and bizarre looking.