Created attachment 151099 [details]
Here you can see the area-selection-screen for the screenshot. There although in this picture only barely visible you see the spectacle window starting to minimize. (Increase brightness if needed)

SUMMARY
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STEPS TO REPRODUCE
1. Press "Print" to open Spectacle
2. Choose "Rectangular Area" as Screenshot option
3. Press "Record a new screenshot"

OBSERVED RESULT

The menu to select the area for the screenshot contains the spectacle window while it's minimizing.

EXPECTED RESULT

The menu to select the area for the screenshot doesn't contain the spectacle window while it's minimizing.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Fedora/KDE
(available in About System)
KDE Plasma Version: 5.25.3
KDE Frameworks Version: 5.96.0
Qt Version: 5.15.5

ADDITIONAL INFORMATION