The initial mandate for the final (at the time Mk5) War Machine suit in Endgame was a bulked-out suit with heavy anime-style boosters for an anticipated final battle in space. This was an early pass at adding an "armored Veritech"-style booster pack to what was at the time the approved Mk 5 suit design, something that would fit nicely over the already bulky backpack ultimately appropriated for the Mk4 suit in Infinity War. In the end the battle was moved to Avengers HQ and the design was replaced with Adi Granov's badass Iron Patriot Mk2.