I use Backblaze B2 as one of my offsite backup destinations. I have my photo collection there as well as a bunch of other archival stuff. As part of my Setapp subscription I found CloudMounter as one of the apps included. In short CloudMounter will take your OneDrive, Dropbox, etc. accounts and make them look like drives in Windows Explorer/Mac Finder. This is useful for many reasons but I use similar software (ExpanDrive) for the same thing.
Unfortunately CloudMounter doesn’t take into account that B2 charges not only for storage but calls to their API. Those calls are split into billing tiers. So today I noticed (via Little Snitch) that CloudMounter was constantly sending and receiving from the B2 bucket I had set up. I have caps set up on the API calls and eventually I got an email today that my caps had been reached. Thanks CloudMounter! Needless to say that software is no longer on my Mac.