syncdefaultsd constantly uploading -an iCloud problem in Big Sur

Syncdefaultsd runs almost constantly in the background uploading Gbs of data since I updated to Big Sur. This kills my download bandwidth making the internet almost unusable (downloads need some upload bandwidth, and I have very little). This appears to have been a recurring problem for others that has cropped up over the years. Previous suffered have determined that this is an iCloud issue, and I can confirm that removing iCloud stops the problem. However, if I have iCloud setup but turn off all options (no keychain, drive, photos, etc.) then syncdefaultsd goes back to uploading something? I let it go for a couple of days to see if it just needed to finish uploading whatever, but even after uploading 2 Gb it was still going strong, :-(. In the past users have stopped it using Little Snitch, but I really don't want to pay $47 to fix a problem I shouldn't have.