New issue since 12.1.?. Does not occur in 12.0.?:
Pressing ALT+TAB, holding ALT:
- Windows' dialog appears for a fraction of a second
- DisplayFusion's dialog shows up

Presumably that's the root cause for this annoying issue:
A short press of ALT+TAB to switch back to the previous window, brings the other window to the front and then immediately switches back to the first window.
Both dialogs (Win & DF) perform a "switch to previous window"
I have to press ALT for a longer time to really bring the other window to the front.

Settings:
"Show on primary monitor only, show all windows"
[x] Show window text below each Alt+Tab item
[x] Show window icon below each Alt+Tab item
[-] Show close button
[-] Show the Desktop window

Thumbnail 150x100