The news from the development team tonight is that Google+ is deprecated (I had not heard that term used in this context before tonight), and Viva should disable the Google+ Sign-In feature.
It was only a matter of time before Google+ died. The statistics were around 0.5% of Google users are active on Google+.
“Google+ Sign-In” will be migrated to “Google Sign-In”. https://developers.google.com/identity/sign-in/ios/start
With the Android version of Viva only days away from launch, maybe this should be the final tweak before version 1.0.