I guess the brake pads may have been worn for too long and the iron boat plate inside came into contact with the rim. The iron came into contact with the rim and was damaged.
I guess it's possible that the brake pads have been worn out too much after being used for too long. The iron boat plate inside has come into contact with the rim, and the iron has come into contact with the rim, causing damage
I guess it may be that the brake block has been worn for too long and worn badly. The iron boat plate inside is in contact with the rim, and the iron is damaged by contact with the rim.