Are you using Thrustmaster TCA Sidestick? If so, I think there’s a hardware issue where the twist rudder controls are overly sensitive even on idle.
What I usually do with mine is that I shake the sidestick a little and do a full rudder movement left and right and repeat for a few times, while having at least 15% Deadzone on the Z axis.
This usually stabilise the rudders once you do this. At least for a while until it starts to be overly sensitive again. In that case, pause the sim, shake the sidestick, do full rudder left/right movement a couple times. And unpause the sim, and that should stabilise it again.