I am running macOS Sonoma 14.0 and Dropbox Professional.
I moved back to Dropbox a few days ago after several months of testing the waters with iCloud. (That won't happen again -- I'm glad to be back!). When I re-installed Dropbox, it allowed me to specify where to place my Dropbox folder, so it went into /Users/username/Dropbox. I moved tens of thousands of files from Apple's iCloud folder over to the new Dropbox folder and it sync'd without a hitch. All's well at that point.
I later completed the upgrade to Dropbox's File Provider beta. It was a couple days ago as I had not previously been aware of the File Provider beta and requirements. As expected, Dropbox created a folder for syncing within /Users/username/Library/CloudStorage/Dropbox, as required by Apple's API. It appears to have synchronized my folders and files to the new location.
I noticed, however, that my original folder is still there under /Users/username/Dropbox.
I am surprised it synchronized to the new location but did not delete the old one.
Is this a safety precaution in case something goes wrong? Is it safe to delete the old folder? It did not tell me that it was leaving the original folders/files in place, so I am reluctant to delete them without knowing for sure that Dropbox is no longer using that old location.