The Disappearing Windows
With recent macOS updates, Apple introduced a new default behavior designed to make accessing files on your desktop easier. If you have several application windows open and you accidentally click anywhere on the bare desktop wallpaper, macOS automatically swoops all of your active windows off the screen, hiding them at the edges to reveal a perfectly clear desktop. While this looks visually impressive, it is highly disruptive for users who frequently misclick slightly outside of their browser window or who rely on keeping a sliver of the desktop visible as a visual anchor. One errant click completely destroys your workspace layout.
Disabling the Wallpaper Click
To maintain your workflow and stop macOS from automatically showing the desktop when you click the wallpaper, you must disable this specific window management shortcut in the system settings.
Click the Apple logo in the extreme top-left corner of your screen and select System Settings. In the left-hand navigation sidebar, scroll down and click on Desktop & Dock. In the right-hand panel, look for the section titled Desktop & Stage Manager. You will see a setting explicitly named Click wallpaper to reveal desktop. By default, this is likely set to “Always”. Click this dropdown menu and change the selection to Only in Stage Manager. The change takes effect immediately. Now, when you are working normally (outside of the specific Stage Manager mode) and you accidentally click your wallpaper, nothing will happen; your active application windows will remain exactly where they are.