Even after a clean install. That's disappointing. I was thinking about running a repair installation but there would be no point if a clean install doesn't fix this.
Guess we have to wait for the slouching beast, Microsoft, to fix this issue. Sigh...
I guess just keep posting via MS's Feedback Hub.
In Settings, go to System & scroll to bottom, select About, scroll to bottom again and punch Give Feedback.
Select:
Category - Files, Folders, & Online Storage
Subcategory - File Explorer
Then search for: "Sometimes on the latest version of Windows 11, File Explorer will take foreground focus by itself and go on top of the app I was using"
Then upvote it. You can post there as well...
It does look like MS is looking into this: