Dark mode is gaining more and more popularity among applications, both desktop and mobile, as it not only reduces eye strain, but also saves battery time. And both of these requirements are just as important to team members as to others.
This is why Slack beta users on iOS have been treated to the dark theme a few days ago and that the same feature is being rolled out on Slack beta on Android. However, the dark mode of Slack is not a real black, like that of Messenger or Reddit, but rather a gray color a little darker than the dark theme of Windows 10 as a whole.
Keep in mind, however, that this only applies to your chat rooms and your settings menu. On the other hand, the left sidebar where you see the list of all your Slack threads and direct messages still retains the innate purple color of the application.
Dark mode is only available for those who have registered for the Slack beta for the moment. If you have not already done so, you can go first to the Google Play Store listing of the app and join the beta program.
Once there, you will need to update the beta version of Slack to its latest version, then close the application. Once you re-open Slack, go to the settings menu and look for the Dark Mode Down option.