In any release I've ever used in the past, this prompt would dissapear the moment I moved the mouse.
The cleanup of Windows temporary files is running as I return to an idle desktop. Moving the mouse or running any program will not dismiss (slide away) the messsage - like before.
Clicking X will close the message with the task are complete message sliding in. That message does time out after a few seconds and slides away.
22.0.0.67
Win7Pro x64 SP1