Before you do anything, use a reference of some kind, ie. view from the top when the FD is trimmed so the outer plate is directly over the outer chainring, to confirm that it's actually moving. Or try applying some twist by hand and see if it does.

If it is moving, I doubt the fitting is bending, especially because it's moving in the unlikely direction. So look for a cause, like excess shift pressure when upshifting. You can try a traction material such as CF assembly paste or medium grit lapping compound to keep the FD from slipping in the fitting, but shouldn't need it.

If it is moving, you have another issue causing it, such as the FD being too far forward with respect to the chainring, and need to find what it is.