Notification filters are now back in the Ad Optimizer. On the Campaigns, Budgets, and Entities pages, you will be notified immediately of any problem so that you can address them right away. Opportunities for optimization are also indicated. You can now filter the affected campaigns or budget periods directly in the tables.
You can easily show or hide the notification filters via the settings in the "Page Elements" on the Campaigns and Budgets page. Notifications are arranged in a slider directly above the table. Within the bar, they are sorted by criticality (critical, important, informative).