MLS-99 Said:
"email not syncing since iOS 16.2: Upgraded both iPhone and iPad to iOS 16.2. In the apple mail app … If I read or delete email on my iPhone, it updates the iPad correctly. If I read or delete email on my iPad it does NOT update on the iphone. I have deleted the gmail and readied from both devices and restarted both devices."
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Try a New gmail App Password:
Try creating a new App Password. Your App Password may need to resync - something typical after update installations. You would log in using that password, rather than your email password. For Instance, here Is the site for gmail: Sign in with App Passwords - Google Account Help - Google