For years, Microsoft has wrestled with modernizing the File Explorer app on Windows. Over the last few years, we've seen Microsoft slowly introduce modern UI elements across the File Explorer interface. Areas like the top of the app, Home page, and details pane have been modernized with WinUI 3, but the rest of the app has pretty much remained untouched.
This means that the File Explorer experience right now is very fragmented, being shared between decades-old interface design and modern WinUI design. Well, it looks like Microsoft is slowly moving to fix that, as evidence that the company is planning to modernize a pretty major aspect of the File Explorer has now appeared.