If there was some explosive devise on board, it could make sense it detonated after descent if it had some sort of pressure switch. Most suspected bomb on board checklists I’ve seen detail procedures to handle pressure switch devices.
Also, what piece is that? It looks like grey paint, aluminium outside and some sort of thick honeycomb structure below. Could that be the nacelle ie? Almost looks like the puncture marks come from the outside in, opposite from expected if there was some sort of severe damage from an engine failure.
Edit: Looks like the nacelles are white, the only light gray seems to be on the wings and pylons. So maybe the punctures could be an engine throwing parts out.