With the A220s, airlines can decide if they want a bathroom window or not, and the feature actually doesn’t involve adding an additional window to the aircraft’s fuselage. Instead, the window is in that position no matter what, baked into the design of the plane. When an airline requests the aircraft from Airbus, they can decide how to use that space. The carrier can choose to put seats in front of the window, or build a lavatory in front of it. If they opt for the lav, they can leave the portal there, or be boring and place a wall between the inside of the lav and the window.