In brief: It seems that Valve is bringing some interesting UI updates to the Steam client for Windows, Mac, and Linux, including a revamped downloads page and an updated library with storage management features.
The changes are currently available in the Steam Client Beta program, which you can join by clicking on "Steam" in the top left corner of the client, followed by "Settings" and "Account." From here, click on the Beta Participation drop-down menu and select Steam Beta Update.
The game downloads page has the most changes. The entire queue can now easily be reordered using drag and drop, and Steam shows the total download progression, including the disk allocation process. "Previously the progress bar would only display the downloading content progress but not the disk allocation process which would make an update appear completed when it was not," the company writes.
Downloads now include icons next to a game's title showing the type of content included in the update: Game Content, Downloadable Content, Workshop Content, and Shader Pre-caching. This icon only appears if the update is not solely game content. There's also a "View News" button that automatically displays the latest patch notes if the game developer entered them, as well as a "clear all" button to keep things clean.
Another big change has taken place with Steam library folders. Not only can you now quickly see where your games are installed, but you can also move them between drives with ease. It's accessed by going to Settings, Downloads, then Steam Library Folders.
There are few more updates, including reduced CPU usage of Steam Input and support for the current set of PowerA Xbox Series X controllers. Valve has published the complete list here. No word when they'll roll out to the public Steam client. Instructions to access the new beta Steam Client can be found here.