Can you just block that element with your adblocker?
FWIW, that’s just a Substack feature. It’s not like the authors all got together and decided they all wanted to make a modal pop up on scroll and interrupt your reading.
I'm not sure I feel like usually a "well-made" site doing this will vary some identifier or something so that you can't just wholesale block them all.
And that's fair, I understand that but they do still choose to publish there instead of their own blog. My opinion on that site is kind of agnostic of the owner of the problem it's more just that I'm not going somewhere knowing that is going to happen when I do.
FWIW, that’s just a Substack feature. It’s not like the authors all got together and decided they all wanted to make a modal pop up on scroll and interrupt your reading.