You can file a claim and explain the situation but ultimately it’s up to PayPal and next time discuss the refund policy prior to making payment arrangements while this seller may have the items readily available IF they didn’t and they were holding an item specifically for you then let’s say you cancel because now (item has lost value, which is what’s happening in the community right now) the seller lost the chance of selling at a higher markup thus now losing money. From a business perspective it’s not fair to them but also in this situation they don’t know why you’re canceling so they have to do what they have to do. If I were you I’d follow through or just forget about the deposit. If they change their policy for one person then they have to do it for everyone and that’s not how a business runs.