No clue. I can't be related to urea injection because that is downstream. The Passat does have a DPF.
Here is the existing fuel routing.
I don't know why they would change anything here related to the engine so I can only assume it has to do with the internal filter housing routing. You must have at least a return and feed for the tank and obviously, a feed line to the engine and a return line. The fuel in the tank and the lines act like a heat sink for the fuel heated by the engine. There could be a line not visible.