That post isn't explicitly about a Firefox Monitor extension, and I could only find this rollout to US users mentioned on 3rd party websites. Those posts include BugZilla links, but they're restricted.

I can easily disable Pocket, Autofill, and Screenshots in about:config, and Firefox support explains that. With this extension, I'm missing a "extensions.fxmonitor.enabled" option.

I understand it's good to build in optional security features like this, but I don't see how it's acceptable to not notify users or provide an opt-out.