The fender liner must not be attached to the bottom Panel and the wind is pushing it back, especially at Highway speeds.
I once drove with the front bumper off after putting in the Intercooler, you know just to make sure all the connections were secure. At about 45 Mph, the wind pushed the fender liner back into the tire. Heard it immediately and slowed down, was right by the house so pulled in to check Out the horrendous noise and saw what had happened. Whoops, bad idea. Nothing was damaged but you could see where it was rubbing. I’m an idiot! LOL.