After adding to your browser:

The original extension is a tool designed to uncover a user's hidden friends list by exploiting the "mutual friends" feature. However, please note that similar extensions like "Marauder's Map" were previously removed from official stores for violating privacy terms. Quick Download & Use Guide

“You will not… use automated means (including bots, scrapers, and browser extensions) to access or collect data from our Products without our prior permission.”

To mitigate these risks, users should only download extensions from reputable sources, carefully review permissions, and regularly update their extensions.