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Why does FeaturedOnly filter in the Finding API not return the same items which appear in the "Featured Items" section of Search Results Page in the website?
The FeaturedOnly itemFilter in the Finding API only returns the "Featured Plus!" items. The website on the other hand returns "Featured Plus!" as well as the "Featured First" items in the search results page. So, the API response and the website results does not match.
Please note that "Featured Plus!" is not enabled on all eBay sites. To find out if "Featured Plus!" is enabled on a site, please call GeteBayDetails with <DetailName>ListingFeatureDetails</DetailName>
Example: Featured Plus! is disabled on eBay US. What results are returned in the API response?
eBay US site (GLOBAL-ID=EBAY-US) does not support "Featured Plus!" items. When you fire a Finding API query with FeaturedOnly itemFilter set to true, API response Featured Plus! items listed on other sites (example EBAY-AU) which are available to US.