I've had Carbonite on my MacBook for some years and a few times used it to recover lost files so the fact that it seemed to get "stuck" on some files, and I needed their tech staff to fix this remotely, was something I'ld forgive.
Not any more. On 26 June 2021 it stopped backing up. Each time I pressed "resume" it immediately stopped. No help from tech staff who just pointed me to their FAQs pages.
Mysteriously the MacBook's 250 Gb hard drive was being used up. Four weeks after 26 June it filled up completely, I couldn't open Mail or even TextEdit. I didn't suspect Carbonite at the time but...
At the local Apple store, a staff member overviewed disk usage with a tool called DaisyDisk. He found the Carbonite program (client) had written 113.4 Gb of error messages to a log file—without ever telling the folk back at Carbonite server-side that something was wrong. There was no disk space to make a screenshot so I attach photos of the DaisyDisk display, that I took with my phone. He deleted the log and the machine came back to life.
Since I reported this, Carbonite staff have completely blanked me. There have been no responses to my emails, though I quoted Case number etc that had they issued me previously.
Carbonite might have offered an OK service once, but now—maybe the best is if we all help it to implode.