Interesting to see that on this Build 23403 and also on Canary 25314 they may have fixed a problem that was reported years ago and never fixed till now.
Finally, the window showing the progress of the System image backup opens and stays in the foreground instead of hiding behind the other open windows.
Not sure if it was fixed by coincidence or intentionally, but it was a pleasant surprise.
Better late than never, I hope they don't break it again. 😉