Desktop icons are invisible when window scaling is set to 2x
When you place multiple files on the desktop let's say via new file context menu or URL drag 'n drop from Firefox then the icons will be placed on the left side of the screen from top to bottom. The problem is Xfdesktop thinks there is double of the space vertically because it doesn't consider the window scaling which is set to 2x under Settings->Appearance->Settings->Window_Scaling. So when there are enough icons placed vertically they will get out of screen space at the bottom of the screen. I tested this on Xubuntu 21.04.