How do I Reauthorize Screen Sharing for Quicktime?
You can reset the screen recording permissions for QuickTime Player using tccutil:

tccutil reset ScreenCapture com.apple.QuickTimePlayerX


After running this command, you need to quit QuickTime Player (if it was open). Then open QuickTime Player again and choose "New Screen Recording..." from the File menu. That will cause the prompt dialog to pop up again so you can grant permission for Screen Recording.