Dark Mode is a color scheme that darkens background windows and controls, so it directs your focus to what you are working on.
Stata has lots of windows, including the following:
Usually, the Results window shows and the others come and go. When lots of windows are up, you can push them out of the way.
Alternatively, you can now tab these windows together. Tab them and only one shows at a time. Click the tab, change the window. Tab them all together or just some of them. You can see an overview of all your tabs in one window.
Tabbed windows are a great alternative when screen real estate is limited, such as on laptops.
Here's an example of a tabbed window: