This new functionality means that WhatsApp , one of the most used apps in the world, continues to be updated by finding news that today are valued by users in their user experience.
Dark Mode first of all raises the battery saving of the device that is being used, in this case, the battery of your smartphone since the lighter and brighter colors mean a greater energy expenditure than the dark ones.
Another reason supported by many (not all) is that the dark mode would serve to rest your eyes.
A third reason that users have seen is the possibility of using WhatsApp without being so exposed. In the office, movie theater or in your room before bedtime, dark mode would be more appropriate.
As soon as it is released to the market, WhatsApp will propose different themes to customize your app. Light theme (the usual one), Dark theme (dark mode) and System default (taking by default the mode you use on Android).
Today, few users are using the Beta version of the dark mode. There is still no official release date, but it is promised that it will be released in a very short time.