Only one panel on the rear door in the #511 photo shows the marks. Note also lack of distortion in this panel.
How would the adjacent panels escape similar damage?
Shrapnel propagation in environment full of different objects, toilets, food trolleys, partitions, or even humans - personnel would definetly be at galley during climb - would make a lot of shadows, reflections or ricochets.
You can see similar scratsh near yellow arming lever and some on the right under Airbus - A ...
It is bunch of them on the trim panel which makes them look like blast shrapnel traces...