Use this page from the same URL you use when you see “Error 400: origin_mismatch”.
Add this exact value in Google Cloud Console → APIs & Credentials → your OAuth 2.0 Web client → Authorized JavaScript origins → ADD URI:
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Important: Use Authorized JavaScript origins, not "Authorized redirect URIs". They are different sections.
Steps:
If you use both https://www.trusted-doctor.com and https://trusted-doctor.com, open this page from each and add both origins.