It used to work OK until maybe October 2019, then it stopped working. It used to block while loading friend list, now I think it blocks while logging in. Not sure where exactly it stops, but it doesn't work anymore.

I wrote a couple of messages to WhoDeletedMe support, but I got no reply. I really hope they fix it. I'll be ready to give it 5 stars :-)

October 2020 - it works again! Changed to 5 stars. However, I got a warning (and a forced password change because of "suspicious activity") from Facebook. I wonder if it was this add-on doing its legitimate work.