By at least two ISPs (out of two I checked), but there are sites that track this. And this block has no opt-out, while the "porn filter" one requires you to be

By at least two ISPs (out of two I checked), but there are sites that track this. And this block has no opt-out, while the "porn filter" one requires you to be over 18, so how would you call it? Also because the political rethoric around it is quite precisely "protect the children"...