Facebook sets in active mode the dark function of Messenger, called «dark mode», which had already announced last year, following the trend of the times.
What does this mean; Messenger experimentally attempts to replace the white background with black. The font remains white to be legible, and some fields, such as the search bar, remain gray.
All you have to do to activate the “dark mode” on Facebook Messenger is to send a moon emoji to any conversation. Once you send this emoji, a pop-up message appears at the top saying “You Found Dark Mode!”.
There you will see the new option called “Dark Mode”. Just next to it there will be a toggle button, pressing it will activate the dark mode.
Note, however, that switching to a black background is not available for everyone, since some users who did the specific steps failed to enable this feature.