Does not work. I'm on latest firefox with ecosia.

With the new (in beta) google search 'option dots' at the right hand side of each result, this no longer works, sadly. There's no way to opt-out of the beta features (it seems to be a soft roll-out on google's end.)
It's my hope that this addon will be updated soon, as I love the features it provides. If there's any more info I can give, let me know.

Google's updated their search engine scripts or codes, i believe. As seen through July 2023, the ublacklist dialog has gone missing under the url where it has been always. What was blocked still appears in results despite. Browser wasn't updated, so that's not the cause. There is no way to block them at the moment. Please fix this soon.

You should add the "pause blocking" button.