You've been having the exact same problem I've been having. If you have MSI Afterburner or Rivertuner Statistics Server running like I do, close it before playing Battlefield 6. It may be the reason why you're having this problem, and closing RTSS fixed it for me.
You guys aren't alone with having to face this issue. There's a lot more people out there that are having the exact same problem. Sorry if linking to my bug report looks a bit selfish and mean, but all I want to do is help spread awareness that it's a problem that tons of people are having, and that there's a potential fix out there.
Mouse Look Stutters / Jitters When Pressing Keyboard Buttons | Potential Fix | EA Forums - 13009311
Unfortunately for me this 'fix' only makes it slightly better, the core issue still remains even after closing RTSS and all other overlays, like Discord, Steam, and OBS. Really hope this gets fixed, I wanna play my game! lol
