The rclone api access key was revoked.
A few months ago, I was doing extensive research on personal cloud backups (Backblaze, Amazon Cloud Drive, etc). My requirement was to have client-side encryption synced to the cloud. A modicum of googling led me to rclone. After reading about how rclone works, I immediately made a mental comparison to Amazon's "official" client GUI sync program and thought, "there's no way Amazon has blessed rclone." It would be very risky to invest hours into building custom backup scripts built on top of rclone if Amazon blocks it. Well, it turns out that's exactly what has happened.