Ideas
I've done all that and more. NOTHING changed regarding my PC setup from Monday through Tuesday EXCEPT the BF6 update. It crashed immediately with the infamous Javelin anticheat message. I have no overlays running, adn have neither downloaded, installed or used cheats, ever. EA is free to remote into my PC to confirm.
I repaired the game. I uninstalled javelin and reinstalled it. I ran the game and Javelin as administrator. I uninstalled both, restarted the PC and downloaded all 70GB again and reinstalled. Ran the game as administrator. Result? Same Javelin anticheat message and game crash.
At this point, like you, there is nothing else I can do on my end. I have a $100 game that I can no longer play because EA is convinced, absent anything tangible, that I'm cheating.