It's nothing to do with your browser, its Windows, and you will have to go into windows settings and look through 'Appearance'. Mine does the same but to be honest I thought it was the default setting and wouldn't know how to get onto desktop any other way.
If you right-click on the taskbar, and select Taskbar Settings, you can then uncheck the "Use Peek to preview the desktop ..." option. Although that only happens at the bottom right corner of the screen anyway, but hopefully that's what's causing it.
Found it: go to Windows setting/personalisation. Turn off the tab that says 'Use peek to preview the desktop when you move your mouse to the show desktop button at the end of the Taskbar'