eBay's feature upgrade fee refers to the fee that sellers need to pay to upgrade certain specific features of their product listings on the eBay platform.

Specifically, the upgrade feature fee may include the following:

1. Category Icon: Allows sellers to display icons of specific categories in product listings, which helps to highlight the characteristics of the products.

2. Featured Listing Icon: Allows sellers to display special icons next to the product titles in the product listings to attract more buyers' attention.

3. Bold Listing Title: Allows sellers to bold the product titles in the product listings to increase the visibility of the products.

4. Featured Store Logo: Allows sellers to display featured logos on their eBay store pages to enhance the store's image and popularity.

5. In-Person Pickup Store Logo: Allows sellers to display an in-person pickup store logo on their eBay store page to attract more buyers who want to trade offline.

It should be noted that the cost and availability of specific feature upgrades may vary depending on the seller's region and eBay platform regulations. In order to obtain the most accurate information, it is recommended that sellers refer directly to the eBay official website or consult eBay customer support.