The oAuth2 logon say 'not verified by Google'...

[marcogaio]

The plugin does not work anymore.

When i try to logon, OAuth2 appear, i can insert user and password but after then i got in OAuth2 screen:
Funzionalità Accedi con Google temporaneamente disattivata per questa app
Questa app non è stata ancora verificata da Google e non può quindi usare la funzione Accedi con Google.

roughly translated from Italian:
Feature Google Access temporarly disabled for this app
This app is not just verified by Google, and cannot use the feature Google Access.

Thanks.

[AJCxZ0]

Confirmed with Thunderbird 68.7.0 + gContactSync 3.1.7 and long-existing connection to my @gmail.com account, each upgraded multiple times over the years since setup.

From Address Book, right click @gmail.com book,

1. Select Sync Now
   Pop-up window gContactSync Warning warns,

Your authentication token from Google has expired. 
Please click OK then enter your credentials to get a new token and Synchronize your contacts.

2. Click [OK]
   Window gContactSync Refresh Token opens with sign-in prompt.
3. Provide Email, password and 2-Step Authentication
   Get message,

Sign in with Google temporarily disabled for this app
This app has not been verified yet by Google in order to use Google Sign In.

Removed and re-installed gContactSync Add-On with no effect on this issue.

[jdgeenen]

I'm working on domain verification. I don't know what happened to my original request, but I resubmitted one last week and heard back with some additional steps. Apparently I need to make a YouTube video demonstrating the process, so it may take some additional time.

[marcogaio]

Some news?