Assuming Simple Delivery was used you are supposed to be protected if the item is lost/damaged in transit. That means ebay will pay the refund, not you, when the buyer opens a claim.
Also from November 2025 (I don't think we have an exact date yet but surely has started by now) if tracking shows delivered within 30 days after a seller has refunded, eBay will reimburse the item cost.
If neither has happened contact ebay about it by requesting a callback on here:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid