A buyer is given 30 days buyer protection so can return items,so if they open a return request citing item damaged you will have to refund or ebay can do it for you if you refuse,and place a defect on your account.
You would have to provide them with a prepaid return label at your cost,and while you may or may not want to pay any more for something broken to be returned,the buyer could decide it's to much bother to go to the point of packing them up and posting back 😉
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