Google Sheets Plugin : Error 400, redirect_uri_mismatch

I whipped up a Flask app that allows interaction with the Google Sheets API. I registered an OAuth client ID, and the JSON metadata file gets verified on the ChatGPT site when I try to install. However, when I click “Log into google” as prompted by the ChatGPT site to log in to the Google Sheets API, I receive an Error 400 with the message “redirect_uri_mismatch”.

The error URL is:
accounts google com /signin/oauth/error/v2?authError=%3D%3D&client_id=

In my manifest file, I am initiating the OAuth flow with:

"auth": {  
"type": "oauth",
"client_url": "accounts google com  /o/oauth2/auth", 
"client_id":"client_id_here",
"client_secret":"client_secret_here",
"redirect_uris": [      
chat openai com  /aip/plugin-<pluginid>/oauth/callback       
],       
"scope": "www googleapis com  /auth/spreadsheets",  
"authorization_url": "oauth2 googleapis com   /token",       
"authorization_content_type": "application/json",
"verification_tokens": {    
"openai": "token"  
}

The REDIRECT_URI is:
chat openai com /aip/plugin-/oauth/callback

This is the approved redirect URI I have configured on the Google Developer Console for my OAuth client ID.

Curious why am I receiving the redirect_uri_mismatch error when the redirect URI in my code matches what is configured on Google’s side.

I appreciate any help in troubleshooting!

Thank you,
Alex