Google OAuth - http redirect issue - ODOO 18.0

It seems that clicking on Connect your Gmail accout in odoo fails because of a 400: redirect_uri_mismatch error.

I have attempted everything in the documents however something isn't lining up and I do not believe it is my configuration.

HTTP > HTTPS redirect is working correctly on my site/server through my reverse proxy

reply from Google:

You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy.

If you're the app developer, register the redirect URI in the Google Cloud Console.
Request details: redirect_uri=http://myhostnamehere.com/google_gmail/confirm flowName=GeneralOAuthFlow
[Related developer documentation](https://developers.google.com/identity/protocols/oauth2/web-server#authorization-errors-redirect-uri-mismatch)

If I try to visit: http://myhostnamehere.com/google_gmail/confirm

I do get the FORBIDDEN error message - however I have updated the google plug in as described in the documentation and that hasn't fixed it. This is also a new installation so I would assume the latest plug in would have been installed.

Forbidden
You don't have the permission to access the requested resource. It is either read-protected or not readable by the server.

I am stuck unfortuantely at this point to understand how to move forward.

Start by comparing the redirect_uri shown in the Google error with the OAuth redirect URI registered in Google Cloud Console, then review the HTTP-to-HTTPS reverse-proxy behavior for /google_gmail/confirm. Done means the generated redirect uses the correct HTTPS URL and the Gmail connection completes without the 400 mismatch or forbidden response.