Recently, Microsoft has enabled a new installation boot interface in the Windows 11 development version, abandoning the purple background that has been used for many years. It is more like the interface of the media creation tool (i.e. MediaCreateTool). During installation, you can choose a new installation, repair the computer, and start the old experience. The old experience here is the previous installation process with purple background.
However, after research by enthusiast @XenoPanther, he discovered that this so-called new installation boot interface has been available for several years, but Microsoft has not enabled this new interface in the past.
Tests show that this new installation experience can be started through the command line at least in Windows 10 Build 21996 (released in 2021), and Windows Central stated that in fact this new interface can be traced back to the Windows 10 Technical Preview (Technical Preview) released in 2014, and the Windows 10 RTM version was released in 2015.
It is unclear why Microsoft has only enabled this UI interface until now, and this UI does not match the existing style of Windows 11. Microsoft has not said that it will update it before releasing it.