This.The damage to the spring is the clue. The spring was not fitted properly in the first place which means the brake pad was not releasing from the rotor on one side and being presented to the rotor at an angle when the brakes were re applied. The accumulated rubbish on the pad shows that it was not being wiped......it only gets wiped by the rotor if the contact is along its full width front to back.
Those pads are toast...........best to check the rotor for damage as well.