Shinigami eyes is a browser extension that was meant to mark someone as trans friendly or not trans friendly, based on user data and guidelines. A username/site/etc would be marked as green if they were trans-friendly. Red meant not trans friendly.
Due to the developer (developers?) being a trans radfem (meaning they believe that anti transmasculity doesn’t exist and afab transfems are trolls (when the latter is usually intersex folks) and intersex people are inheritly anti-trams and “theyfab” isn’t a slur… etc.), SE has basically become useless. People who will call enbies “theyfabs” get marked green, while people who believe in anti-transmasculity or believe that sex isn’t binary get marked red.
