My macOS computer is downloading gigabytes most days through iCloud and I want to find a way to stop the repeat downloads.

I used this command to find out what is being downloaded:

brctl status

It seems to be media and video tarballs from Whatsapp backups from my iPhone

I don't understand why my computer needs to download these iPhone backups and I haven't found a way to stop the downloads from happening. I also don't understand why these aren't checkpointed in a way so that all of history doesn't need to be downloaded each day/interval (presuming that is what's currently happening).

Does anyone have any ideas for a fix or even next steps?