@Moon Websites The endpoint https://api.cognitive.microsoft.com/bing/v7.0/spellcheck/
was used for bing search service resources which were created under Azure cognitive services.
The bing search API has now migrated to a new endpoint https://api.bing.microsoft.com/v7.0/SpellCheck
for any new resource created after October 30th 2020. I believe you have created a bing search resource recently, In that case please use the following endpoint with the subscription keys from azure portal to get a valid response.
https://api.bing.microsoft.com/v7.0/SpellCheck
You can also try to follow the quickstarts under bing documentation for help.
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