quanggn said:
"add a gmail to mail on iPhone 13: I couldn't add my Gmail account to my iPhone 13 Mail running iOS 16 latest version a few weeks ago. This problem also occurs with friends around me who use iPhones. This is very inconvenient because Google calendar and contacts do not sync on the iPhone."
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Using a Google App Password:
When setting up gmail, you need to create and use an app password. You would log in using that password, rather than your gmail password. Go Here: Sign in with App Passwords - Google Account Help - Google. If you already have one, then remove the old app password, and create and use a new one.