I've had this add-on for several years, and I considered it useful until it came to light that in the past couple of years it's been marking certain people as anti-trans for... supporting nonbinary, intersex, and transmasculine people? I don't know what happened here, but this means that a tool that was once meant to help a vulnerable set of people has now turned into some sort of guessing game as to how reliable it is.
I rated this two stars instead of one because I've only encountered this issue on Tumblr whereas everywhere else (especially Twitter) it's been accurate. The only reason I still have it is to try and correct some of the falsely flagged ones I see.