Has that front door panel ever been removed for any reason? Speaker change? Regulator or Actuator replacement? Door handle warranty work?

The door panel is attached to the frame by metal spring tabs which lock into specific holes on the upper section of the panel. What might have happened is the panel popped out of the tab and when someone tried pushing it back into place, the spring tab was bent out of place now preventing the door panel from correctly locking back into position.

My advice: Remove the door panel and inspect the tab to either replace or bend it back into position. There is an artice on how to remove the panel in this site. Thats probably the only way to cure this rattle issue.