The navigation bar will replace the current tabbed interface that sits at the top of the chat list. This gives users the option to access Chats, Communities, Status, and Calls from the bottom by cycling through a more clearly labeled navigation system accentuated by its corresponding icons.
Current WhatsApp UI on Android | Source – Phone Arena
The bottom navigation bar switches between a dark and white color scheme, depending on your theme choice. This is the same navigation bar that is used on the iOS version of WhatsApp, and it is more in line with Google’s design guidelines for Android apps.
Light vs Dark Bottom Nav Bar | Source – Wabetainfo