The file in app group container is still exsits when I install again after deleting the app?

I have copied an sqlite file from document to app group container. I found that if I delete the app and reinstall, the file is automatically created.

How is that happed? The app group container is not just a folder and can be synchronized by iCloud?

I cannot find any informations about the feature. If there is, please show me the link, thanks

The file in app group container is still exsits when I install again after deleting the app?
 
 
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