What's new in Facebook Messenger 528.0.0.0.64
From version 349.0.0.7.108:

We update our app regularly to make it even better for you to easily connect to the people that matter. Update to the latest version to get all the new features and improvements. This release includes:

Split Payments—a new feature in group chats that makes it easier to share rent, travel, and other expenses with friends and family.