iCloud on Windows unable to download photos beyond a certain point

I installed iCloud for Windows and it was able to download 14,668 photos out of approximately 36,000. Once it hit that number it just got stuck at "Initializing..." and would not move further -- tried common recommendations like leaving it on for 3 days, waiting 60 seconds to key last digit of 6 digit passcode, etc, and nothing worked.

I installed iCloud on another Windows PC and it did the exact same thing -- 14,668 out of 36,000, not moving any further. That led me to think there was maybe a corrupted file it couldn't move past.

I logged into icloud.com to view the Photos there, and the file after the last one downloaded was a video file made by the Wonder app called video0.mp4. I looked on the PC to see if it had downloaded any of these, and I saw this --

video0.mp4

video0(1).mp4

video0(2).mp4

...

video0(500).mp4

This wasn't the same video over and over -- my daughter just saved a lot of videos from this app over months/years, and apparently it names all the videos it creates video0.mp4. She was OK deleting these from her iPad, and after that I was able to reset and download everything from iCloud Photos to Windows without issue. I suspect the error was related to Windows 11 or the iCloud client not wanting to create a video0(501).mp4 -- maybe it is limited to 500?

At any rate, I spent a week figuring that out and so I hope it helps someone else.