@Anatoli Katotoikidou The most likely reason that this is failing is because the 3rd party application that you are using is referencing the endpoint to api.cognitive.microsoft.com
instead of api.bing.microsoft.com
Azure bing search API moved from cognitive workspace to bing workspace in October 2020 and this change means any new bing resource created after Oct 30th 2020 will refer to api.bing.microsoft.com
and the corresponding changes need to be made in the application to ensure you hit the right endpoint. I would recommend to contact support of the 3rd party application or you can use the endpoint directly by using the steps mentioned in the document.
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