After I re-installed DeskScapes I tried to duplicate the issue and it didn't happen. But that was a couple days ago. Today when I switched my KVM to my home PC (which disables the 3rd monitor and enables the two primary monitors) the issue occurred again.
I was able to use Zoom to record the event. The video shows much slower flashing than was actually happening. When live it switches images as fast as it can which seems like about 8 times per second.
Note that when I pause DeskScapes, one of the two stops and the screen works as if there is one animated background running. Here is a link to the video shared from OneDrive: DeskScapes Flashing Video. The video requires the password "Stardock".
To answer your specific question, restarting Explorer does make the problem stop.