Gmail for Android rolled out a new tweaked compose button which is far different from the style introduced last year.
The floating action button (FAB) in the bottom-right corner of the inbox screen is no longer a circle. Instead, it’s an oblong-shaped with a new pen icon instead of the multi-colored plus sign. The button will automatically transit into the pencil icon while scrolling. It is not a very big change and other Google apps such as Google Drive still have the ‘+’ icon for composing.
Selecting each interface, inbox type, and display option will show real-time changes in their inbox so they can see how the settings work in real-time. The feature will be made available to all G Suite customers as well as users with personal accounts.