PayPal will only step in, if the buyer opens a dispute and it is escalated by either party within the first 20 days. Once involved, PayPal will review the case and make a ruling. Make sure you meet the requirements for coverage as much as possible to the best of your ability but PayPal has sole discretion whether to cover you or not. Seller Protection is not a guarantee and has it’s limitations. They can rule against you to avoid a chargeback should the buyer lose the PayPal dispute which can take longer to resolve and could cost you more than simply refunding in the first place then focusing on your next sale. Can’t please everyone as long as customer complaints in general are kept to a minimum.
You can also just issue a refund or make another arrangement with the buyer that you are comfortable with to by pass a drawn out PayPal dispute.