Same issue here as well! I noticed it very early in the patch and it is driving me crazy. Completely unacceptable by Dice that this is not getting acknowledged. Any keyboard input that is done while moving the mouse hitches it. Some lobbies are worse than others and sometimes its different keys doing it. The best way to describe it is it feels like the mouse's polling rate gets lowered to 125hz every time you do any sort of keyboard input like swapping weapons or crouching etc. Making the game completely unplayable for many people like myself. It is just not a smooth experience and I it is very game breaking. I have reinstalled the game twice and even fresh installed windows on fresh default bf6 settings and it still occurs. I tried different mice's and keyboards even swapped out pc parts like CPU and GPU It is all on Dice's end and the hitching is so bad I am not even bothered to touch the game until it is fixed. Funny thing is you can barely tell the hitching on recordings because of the framerate of the clips. The dev's have to just test it for them self in the training ground or in any multiplayer lobby to see the issue.
https://x.com/StichyFPS/status/1999324998356684976
Clip of another player having the same issue:
https://www.youtube.com/watch?v=-L2WdnQ_Tmw
SOLUTION:
So after intense amount of testing drivers, reinstalling windows, trying different Nvidia drivers and different things. I realised FTPM 2.0 was still disabled since launch as it was not required to play the game!
Enabling FTPM 2.0 in bios and erasing Secure Boot data/resetting the keys to Secure boot. Disable Secure boot and Re Enable it. after the 1.13 patch fixed all the issues with keyboard and mouse input hitching!!!
Update:
Hitching is back after 10 hours of hitch free gameplay...