I have found this new room layout:
As you can see, the button to open the doors is placed over a pit. Is this a bug? How am I supposed to get out of this room without flight? Am I supposed to just wait for the doors to open automatically?
It's hard to say from the image, but there's no pit in the upper right corner of the room. There's a small pit just above the right entrance and that, combined to not knowing the color palette of the new levels tricked me into seeing a pit that wasn't there.
So, to get to the button, you can just walk there.
The only way to get out that room without flight seems to be bombing a door.
It's very strange because it's unusual, you should be able to clear a room without any special power. Maybe there are different mechanics that work for flooded level that we haven't discovered yet.