Night mode is an automatic setting which takes advantage of the new wide-angle camera that's in the iPhone 11 and 11 Pro models. It's equipped with a larger sensor that is able to let in more light, allowing for brighter photos when the light is low.
macOS Catalina Now Available
Apple Testing Notifications on iCloud Website
Apple introduced a new notification system in iOS 5 and has announced that a similar feature will be coming to the Mac in the Mountain Lion operating system this summer.
It's possible that Apple will include syncing code in iCloud to share notifications across devices, for calendar alerts and new mail, or the notifications may be used for some other purpose.