Hi Joshua
Welcome to Microsoft Q&A Forum, thank you for posting your query here!
I understand that you are encountering an issue, A 500 error, specifically a "ServerError" with a subCode of "UnexpectedError," indicates that there is a problem on the server side, which is preventing the Bing Custom Search service from being available. The message "Service temporarily unavailable. Please check back later." suggests that this could be a temporary issue.As of now there is no outage issue in Bing custom search. Could you try any other available regions. azure.statusif the issue still persists do create a support ticket.
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