I have a mounted disk ( NAS) icon showing on the desktop. For reasons nobody can explain this shifts around when I do various things. EG open Automator, photos, a Pages file, a Bookends (citation software) file. In one case I connected my iPhone, opened iMazing and the disk icon moved across the desktop.
In most of those cases there is no apparent connection between data on the NAS and the particular app; it seems to happen more or less at random.
It has been suggested that removing the finder DS_Store file *might* provide a solution. I am aware there are other means of accessing the NAS but deleting only the Finder DS_Store file appears risk free and worth a try.
I'm currently in the user account but I imagine the terminal command would use sudo and an admin password.
I should add that the NAS is a QNAP. I also have a Synology which for whatever reason does not exhibit the same behaviour.