Some 52.5 million users were impacted by a software update introduced in November that contained a bug affecting a Google+ API. Google+ will sunset all Google+ APIs in the next 90 days and accelerate the sunsetting of consumer Google+ from August 2019 to April 2019. No third party compromised our systems, and we have no evidence that the developers who inadvertently had this access for six days were aware of it or misused it in any way. The bug did not give developers access to information such as financial data, national ID numbers, passwords, or similar data typically used for fraud or identity theft.”]
Source: https://www.blog.google/technology/safety-security/expediting-changes-google-plus/