It almost appears as the spoiler had been fully deployed when it was torn away. When stowed, it's a fairly firmly rooted panel, and flush to the airflow across the wing. I'm trying to visualize the type of odd flow that would pull it out of the wing while stowed.
For constant flap setting, a wing changes load mostly on the forward part with angle of attack. The load on the aft part of the wing where the spoiler is changes very little with lift/AOA, though q increases with speed.
Can't tell if it separated in flight.