eBay is making it easier for both buyers and sellers to cancel orders. Now, buyers can request to cancel an order before it’s marked as shipped by clicking the “Cancel order” button.
Sellers have a three-day window to accept or decline a cancellation request. eBay will automatically cancel unpaid orders after 3 days if you don’t take any action, paid orders will be declined.
Attention FBA sellers: If you use MCF to fulfill your orders you should adjust your process: first, check if the order can be canceled on Amazon. If it can’t, you should decline the cancellation request on eBay within 3 days. If the order is successfully canceled on Amazon, you can then accept the cancellation request on eBay.
eBay recommends responding to cancellation requests as quickly as possible, especially if the request comes shortly after the order is placed.
Additionally, eBay guarantees protection against negative or neutral feedback if you refuse a cancellation, provided that all shipping information is updated in the order. It might also be beneficial to inform the buyer that you cannot cancel the order because it has already been shipped. While this is recommended for customized items, it could offer you extra protection as well.
Read the full article on ebay here https://www.ebay.com/help/policies/member-behavior-policies/order-cancellation-policy?id=5298