Gmail recently got its biggest redesign in years, but not all of the announced features were live right out of the gate. Today, Google has started deploying the new Gmail's "Nudge" feature, which is designed to help you reply to emails you missed or ignored like the lazy procrastinator you are.
Nudge is sort of like a snoozed email, but it happens all on its own. If Gmail sees an email that it thinks you should act on, it can bump it up to the top of your inbox. The email includes a highlighted message telling you how long ago it was received. This is another one of Google's fancy AI features.
All users of the new Gmail will have Nudges enabled by default, but it'll take a few days to be live for everyone. You can disable it in settings if you don't want to be reminded of old emails, you lazy jerk.