It can be confusing, but generally if the label is purchased through eBay’s label system, the contract for that postage is handled through eBay’s platform.

That’s why Royal Mail sometimes directs sellers back to eBay for claims, even when the service itself is Royal Mail. In practice, many sellers find that claims need to be started through the eBay label purchase record rather than directly with Royal Mail.

Unfortunately with lower value items it can end up being more hassle than it’s worth, but normally the key factor is where the label was bought rather than which carrier delivered it.