With yesterday’s Sims 4 Gallery overhaul, The Sims team added a new notification system that pushes notifications through to your game when there’s new activity in the feed. They will pop up when you have new followers, likes, and more.
With the potential for these notifications to become a nuisance for some, it’s nice to know that there’s a way to turn them off completely. Head into Game Options > Other, and tick or untick the “Online Notifications” option. This change takes effect immediately.