In the 2024R2 release, right next to the design tree on top right corner, you will see a right top corner facing arrow symbol (↗) (previously in release 2024R1 and prior, history tracking button would exist in this location), which can be used to dock and undock the design tree and it can be moved inside or outside the discovery window, as per user’s requirement. Clicking on the bottom left corner facing arrow symbol (↙) will dock it back in the top left corner of the discovery window.

If you are wondering where the history tracking button is in the 2024R2 release check this out: Where can I find the history tracking feature in 2024R2 release of Discovery?