Mine does the exact same thing. I think some Broncos are worse than others. I have friends with Broncos and it is not as noticable. For a new vehicle and not being able to drive down the road with your window partially down bc your afraid the window is going to brake and fall off track is...
I have the same issue with my 4door Badlands. If you roll the windows down about 1/4 of the way and hit any bumps in the road the windows will rattle and shake so hard it sounds like the windows are about to brake and fall off the vehicle.
Is there a way to fix this issue?