I tested it on Firefox PC, then Safari on Mac OS. Now just retested it.
Finally also tested on iPad and iPhone, everywhere same result.
Now the subscription widget on your blog works magic.
Now to see the two fields popping, you have to submit two different errors in email field or fix the blur to onblur which then gets the event listener to work.
Alternatively you first enter a mistake email like “mistake”, then “mistake@“ or “mistake@c.” and it looks like further down:
https://codepen.io/cferdinandi/pen/MorBEp