The eBay final value fee is the share eBay keeps per order line item sold. Unlike on most marketplaces, it does not appear as a single line in the statement but is spread across a large number of individual fee types.
How does eBay settle?
Per order line item, and in very fine detail: in the settlement data eBay distinguishes around 45 fee types. Alongside the percentage final value fee there is usually a fixed fee per order; depending on listing type and optional extras, further items are added.
For an analysis this means: a flat rate across everything only hits the actual charge by chance. The fee types have to be read individually and assigned to the order line item.
What comes back on a refund?
Whether eBay credits fees back on a refund, and how much, depends on the reason and the refund route. This also applies to the fixed fee per order. The fee credit on your invoice is what counts. Outbound and return shipping, packaging and advertising stay with you in any case, so a return usually costs more than the lost revenue.
Where do I see the fees?
In the eBay Seller Hub and in the settlement reports. The presentation there is designed around payout runs, not around the question of what an individual item earned; for the contribution margin, the line items have to be set against the orders and your own costs.
45 fee types, assigned individually
The profitkonsole for eBay reads the fee lines individually from the settlement data and offsets refunds according to the credits booked.
Contribution margin, not revenue
Every sales channel in one dashboard: marketplace data and your own costs brought together, per item and per channel.