Thanks for the information. Please refer to this reference document for the correct Bing News Search API endpoint, headers, and parameters. Also, here's a summary of all Bing Search APIs, for each reference, you'd find endpoint details under Reference > REST. Hope this helps.
Sample endpoints:
https://api.bing.microsoft.com/v7.0/news
https://api.bing.microsoft.com/v7.0/news/search
https://api.bing.microsoft.com/v7.0/news/trendingtopics