The bug that caused the data breach was discovered in March this year by Google which was several months ago but they chose not to disclose it as they found no evidence. It started a few years ago in which it exposed the users' private information until the time Google discovered this year. It was a serious technical offense when it happened that it opened doors to investigation. The bug was discovered while Google is working on Project Strobe, an internal audit of third-party developer access to Google accounts and Android device data.
Luckily, following the discovery of the bug, it was eventally patched but about Google+, it looks like some service nobody cares for and especially for the previous controversies Google caused in the past like the integration of the service with YouTube comments and such. Such controversy allowed the indecent and troll comments to be unreportable but that was the past that the controversy was reversed and even then, people use the more popular social networking sites like Facebook, Twitter, Instagram, etc.
The aim of Project Strobe is to improve data privacy for consumers in which things you posted on Google+ will not be collected or even other services, as well as the Third-Party APIs. Not to mention the improvement of the data permission for Android apps.
