I kind of feel like it's partly a way to get a bit outside of the Call of Duty contract requirements.
If they have more powerful hardware they can justify Call of Duty on "Next Box" having the best graphics and just say "well it's not our problem that Sony is still in the PS5 generation, we're fulfilling our contractual obligations, but if you want the best version of the game, buy our new XBox". They could have a window of 1-2 years where they can claim that and try to entice COD players to jump ship.