Mysterious "Cloud Sync" is eating up bandwidth

Cloud Sync is eating up the vast majority of the 10GB/mo metered satellite bandwidth at a remote ranch:

I can't for the life of me find any information about this process, but FYI...

1) iCloud is not in use on this computer.

2) Dropbox is the only cloud service being used, that folder contains 1.3GB total, and far less than 100MB gets changed on any given day (a few XLSX, a few RTF, and occasionally a DOCX or two).

3) Between 09-07 and 09-29, only 1.7GB had been used. In the last 2 days, 2.2GB has been used — and most definitely not by foreground processes. There has been a few dozen emails and a small handful of website visits — with ad- and tracker-blocking turned on — to sites that do not play video (e.g. weather, bank, etc.).

Any insights would be appreciated, especially just what Cloud Sync might be, seeing as it doesn't seem to correspond to anything in particular on the computer, and I can find no documentation about it online.

2012 MBP running Catalina