I have also noticed this behaviour since upgrading my 2015 MBP to Big Sur. Prior to Big Sur I did not notice this behaviour. That said, one thing different for me from others in this forum reporting this problem is that the only folder this is occurring on with me is not one synced to Git. Instead it is one linked to my Fujitsu scanner that is setup to automatically deposit pdf files into this folder once they are scanned. Prior to Big Sur these files would immediately begin synching to iCloud the second that they were created by the scanner software. the latest update before the problem started occurring was MacOS 11.4. To work around problem, I noticed that any edit (to the file that fails to upload) will solve the problem. (E.g. a CMD-C and CMD-P forces not only the copy but the original to upload; A name change will force the file to upload; adding a tag to the file will force it to upload, etc.) I also noticed that if I use a python script to place a file in the folder, or I use the command line MV command to place a file in this folder - the problem does not occur and the file uploads fine. Thus I am tempted to hypothesize that the cause of this issue is a change in 11.4 that perhaps deprecated or broke an indexing function of the file system who's job it is to mark files that have changed for upload. The Git repo process and the Fujitsu sync process may be using an API call that is now no longer triggering the file to be marked for synch. Whatever the case - it is clearly a bug and it is sad that FruitCo developers are not paying any attention to their own developer forum when a topic has 19K upvotes. Wake up Fruiters!