This was some time back. I wanted to write this but forgot. One day when I opened Firefox, it had detected an automatically installed script by windows (came in with the update). It was a forced add-on causing ‘instabilities’. It was a plugin that Microsoft thought Firefox wouldn’t notice. It was intended to send malicious scripts without the knowledge of the user. Nice trick! Eat this!

As expected the savior Firefox detected and asked me to disable it. Here is a screenshot of the addon disable notice.
disable windows force addon