Either the awning shifted on the tube rail, it must be pulled on the tube in order for it to roll evenly so the arms align.
The other thing could be that the fabric has stretched for whatever reason and the reason might have been because it was installed off center. Sometimes the wind moves the fabric off center.
how to : with the awning extended, you have to slide the fabric to the right or left by pushing and pulling each side until the fabric is tight with no wrinkles and it appears close to the middle of the roller tube as possible.
Having a second person would be helpful.
The metal awning arms need to fit evenly in the channel on both sides, without rubbing each other. Expect to push n pull that fabric on the roller tube a few times until you get it right, be patient.