So as far as I know the trimmer in the mig21 is only supposed to be on the pitch axis. However, in my install the trimmer affects the pitch and the roll axis at the same time. They are locked together. I've linked a video where it is demonstrated with the control map. The small diamond only moves along the vertical bar. However the large diamond for the actual input also moves to the side (I have a FFB joystick, MS Sidewinder 2). Both movements are controlled with the standard trim control (LCtrl+T/LShift+T), which is the only manual trim entry in the controls.
Another peculiar thing is that the AP is also affected by this. Whenever the AP applies a large amount of trim, the aircraft will roll to the side before the AP corrects for this. The roll trim doesn't go away once you turn the AP off.
It appears to happen with only my install. On I havent found any other cases and no one seems to experience it on MP servers.
I already tried reinstalling, resetting my controls, turning off FFB, checking the input .lua's and rebinding the trim key.
I have no idea what to do about this.
Demo: