Expected to roll out to Android and iOS devices in the coming weeks, Facebook Messenger 4 comes with a simplified white interface that only sports three tabs, and it also comes with the ability to add color gradients to chat bubbles. In the future, this mobile app is also expected to get a Dark Mode.
https://www.notebookcheck.net/Facebook-Messenger-4-goes-all-white-and-only-sports-three-tabs.345401.0.html