Flushing the toilet pumps (fresh) water on the ground
I've got a 2015 Flying Cloud FB Bunk and it's been doing this since we bought it new.
When using the electric flush to add water to the tank, the water pump kicks into action at full speed (no other water source runs the pump full speed - usually it phases up and down as it pumps). The toilet will fill with water, but somewhat slowly. In the meantime, a little pipe right behind the wheels on the road side jets out fresh water.
We're losing a lot of water from this. and I don't know the purpose of that little pipe. We're under warranty and will get it in eventually, but since we live in it and Airstream service places are booked out for months, it's hard to predict where we'll be and schedule something. It's not pumping water inside the trailer, so I don't think it's an emergency, but it's wasting so much water it makes it hard to boondock for more than a couple days at a time.