I have Power Toys version 0.74.1 (latest I think).
I doesn't seem to have a File Explorer option.
I am convinced that this problem we are all having is due to Microsoft updates in Windows 11.
Mine used to work fine until I had an update which caued the preview to vanish. Then after another update I now get a thumbnail in the top left of the preview pane, which is useless.
If anyone who works for Microsoft reads this, I would be very happy to hear his/her response.