That's a drawback of using WinSCP drag&drop shell extension.
https://winscp.net/eng/docs/dragext#drawbacks
You can use Temporary folder approach instead.

When I take a remote file in winscp and drag it to a Windows desktop then it does not drop into the location where it is placed but instead defaults to the leftmost portion of the desktop that is unpopulated with icons. All files dropped will stack alongside. When you have a number of similar icons and several programs running it can confusing as to the exact location of the file.

When I use other tools to drop files to the desktop they remain exactly where they are placed, tools such as WSFTP place the file exactly. WinSCP should function the same way.

I have observed this behaviour in Win XP.