Xiaomi is constantly working on a dark theme in its MIUI 11 shell. This time it will feature an innovation already implemented in iOS 13.
When it becomes available to users – it is not clear, but MIUI 11 will be able to darken the background image of the screen – in addition to the global “blackness” of the firmware. The way this is implemented can be seen in the screenshot.

Meanwhile, one hundred percent a global dark theme with black third-party applications will appear, apparently, only in MIUI 12.