Various footage of the IFT-2 of SpaceX's Starship show intriguing pattern of, presumably, exhaust gases illuminated by the Ship's 3+3 engines (attached below). While this may be an optical illusion, it does appear that some of the gases are present even in front of the Ship. What are the main components/pathways of the flow of the exhaust gases during such hot staging? Could it be that either back-scattering (off the super heavy booster) or just the (initial) thermal distribution of velocities lead to significant part of the gases actually overtaking the Ship, and leading to the beautiful picture we have seen on Nov 18th?
Note: Both the exhaust velocity and the mean thermal velocities of particles at, say 3500K are of the order of few km/s, and we are dealing with expansion of gas in vacuum.