Though the dark mode isn't officially a part of the Slack use yet and instead is now available exclusively to members of Slack's beta testing program. We'll show you how to turn on the dark mode, but first make sure that you've got the latest version of the app. The workplace collaboration app is now rolling out the dark mode feature for Android and iOS beta testers.
Slack's new dark mode can be enabled through the Settings of the app. You will notice that dark mode is applied to menus, pop-ups, and the headers.
It's the same with Notes - if you don't like the dark backgrounds dark mode introduces, you can switch back this element via Notes, Preferences, and Use dark backgrounds for note content. Just scroll down toward the bottom, and you'll see the "Dark Mode" entry. You will also notice that for dark mode the app uses the dark grey color as opposed to being black.
To do it on iOS you'll want to go to this page, and for Android this one (which will direct you to Google Play). Facebook says it'll be fully rolled out and added to the Settings menu in the coming weeks. If after all these steps you don't see it, try to restart the app.
Instead of dark black color Slack chose to use a dark grey color for the app's dark mode update.
You can enable YouTube's dark mode on the web (for the current browser only) by clicking your avatar, then Dark theme. It is more comfortable than the blinding white mode. You can do so by going here for iOS, and here for Android.
A long-requested feature is finally available on Slack. But why not darken your apps where you can in the meantime?