Ebay Affilate API

[saal-s_3023]

I have Ebay Affiliate API to convert ebay product links to affiliate product links.
This is the API endpoint which I am using:

https://svcs.sandbox.ebay.com/services/search/FindingService/v1?OPERATION-NAME=findItemsByKeywords&S...{apiKey}&GLOBAL-ID=EBAY-US&RESPONSE-DATA-FORMAT=JSON&REST-PAYLOAD&keywords=${encodeURIComponent(productLink)}&affiliate.networkId=9&affiliate.trackingId=${affiliateID}&affiliate.customId=1234

but when we hit this API in return this  gave me this url in response : https://rover.ebay.com/rover/1/711-53200-19255-0/1?ff3=4&toolid=10041&campid=5339015429&customid=123...
when i paste this link in browser it redirects me to this url:
http://shop.sandbox.ebay.com/i.html?_nkw=https://www.ebay.co.uk/itm/295616566041?_ul=GB&ff3=4&toolid...

and it says this url is invalid.