Google Cloud - Migrate impacted OAuth out-of-band flow to an alternative method

Job ID: 34499710

Budget: $10 – $30 USD

Few years ago a developer did an important project for my company using Google Cloud - API Services.
Our booking system runs on Google Sheets. I needed to create a booking-form in my website, coherent with my brand identity, that was able to read and write data from the googlesheet. To my understanding he created an API to do so.

I recently received this from Google, and I need an expert to help me with this. I can not afford any interruption in the connection between my booking-form on the website and the booking system on the googlesheets.

"
We're writing to remind you that the OAuth out-of-band (OOB) flow will be deprecated on October 3, 2022, to protect your users from phishing and app impersonation attacks.

What do I need to know?
As we notified you in the first week of May 2022, any affected authorization endpoint requests will be blocked with an invalid_request error after October 3, 2022. Apps using OOB in testing mode will not be affected. However, we strongly recommend migrating them to safer methods as these apps will be immediately blocked when switching to in production status.

Below are key dates for compliance:

September 5, 2022: A user-facing warning message will be displayed to non-compliant OAuth requests.
October 3, 2022: The OOB flow will be blocked for all clients and users will see the error page.
Please reference our previous email with the subject line containing: “Migrate your OAuth out-of-band flow to an alternative method before Oct. 3, 2022,” for more details.

What do I need to do?
Please see the Making Google OAuth interactions safer by using more secure OAuth flows blog post to learn about the deprecation
Follow the Out-of-band (OOB) Migration Guide to migrate your app to an alternative method.
You may acknowledge the upcoming deadline and suppress a possible user-facing warning message by following instructions in our blog post. All non-compliant authorization requests will be blocked with an invalid_request error when loading Google's OAuth 2.0 authorization endpoint after October 3, 2022.
If necessary, you may request a one-time deprecation enforcement extension for each listed OAuth client ID until January 31, 2023. For clarity, the enforcement for the OOB flow deprecation will be enforced on February 1, 2023 with no exceptions or extensions.
"