Sincere apologies for the issue that you are facing.
I have some comments for you please visit the following link and follow the instructions.
Note: The Finding API uses the same technology used to power the eBay site search.
However, due to application logic employed by the eBay site, site search results may not always match identically with the results returned by the API for similar search criteria.
For example, if you enter an ISBN number only as a search query on the eBay site, the application logic for the eBay site will recognize the format and perform a search by product ID. If you make a similar API request (i.e., pass the ISBN in the keywords field of findItemsByKeywords), the search results are not likely to match those from the site search.
please submit a technical support request here - https://developer.ebay.com/my/support/tickets as more details of your developer account are required to triage the issue and you will not be charged if it is a bug.
eBay Developers Support
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