Facebook says the new site will “now be the web experience for Facebook globally,” adding that
“it’s faster, easier to use and gives your eyes a break with dark mode.”
For those who want to turn on a new design and allow dark mode right away, Steps to follow:
1. Click the down arrow at the end of the top menu bar to bring up the old Facebook settings tab.
2. Click the "Switch to New Facebook" button.
3. Press the same down arrow and turn dark mode from off to.