Old Android phone users will lose Google app sign-in support from next month. These users will get a “username or password error” whenever they try to sign-in to any Google apps loaded on the phone. These include YouTube, Gmail, Google Drive, and other Google services.

source https://gadgets.ndtv.com/mobiles/news/google-gmail-youtube-drive-account-sign-in-support-disabled-september-27-android-v2-3-7-and-lower-2499569#rss-gadgets-all