A lot of us got a big surprise today when we went to comment on people's blogs and got a Captcha box to enter a number to "prove we are human". This seems to only happen on blogs where the comment form is a pop-up window, as blogs with embedded comment forms aren't affected.
There is much ranting over at the Blogger forums here: https://productforums.google.com/forum/?hl=en#!categories/blogger
Google/Blogger said it's our individual third-party cookie rules, but for me it's only broken for blogs with pop-up comment forms, and ALL of us didn't make changes, so I suspect it's something else.
Until then, I've changed my comment for to embedded. I seem to recall people had problems commenting when I had it that way before, which is why I changed it to a pop-up form. We're screwed either way.
I know, I know: you get what you pay for, right?
ETA: I've heard you may still get Captcha if you have the embedded comment form, but I haven't seen it yet. I've also heard you can ignore the Captcha and it will still post your comment. Sigh.