Lets assume the panel was found as shown in the photos...
As DaveReidUK says no visible damage to the countersink holes.
Also no visible bolts or parts of them.
Which might suggest the panel had been temporarily fastened by maintenance with one or a few bolts or temporary fasteners.
Take the lady up. Vibration and force shears off the first. Then the second. Releasing the panel. Little visible damage.
Nothing to see ? I disagree with that. Shedding parts is always a serious issue. Both for plane strikes and striking anything else.
Have not heard about the bracket failing. What damage would you have seen on the panel if it did? You would expect at least part of that attached... With some bolts left... Or not?