I’m sorry if the popup offended you. It’s possible to block such things by using a browser extension such as uBlock Origin, which will allow you to black or greylist 3p requests to services such as Mailchimp that provide that modal.
I urge you to consider the alternatives though. Publishing today happens via a very small number of heavily censored services that decide not only what you can say, but who gets to see it, how often, and when.
Millions seem unfazed that a tiny handful of people decide what they are allowed to read.
Aggressively requesting direct contact information from my audience is one of the few remaining censorship-free ways of communicating with people. I don’t like popups either, but sometimes it is necessary to yell a bit to get people’s attention.
I vastly prefer slightly annoying people (exactly once, see below) to having the only push-based method of communication being censored and surveilled systems like most modern centralized social media. I’m sorry it upset you. There just aren’t any other great options that I know of to ensure that people who want to receive push-based communications from me always can in the future. RSS usage died some years ago and the only remaining feeds people look at are their email inbox and censored algorithmic “timelines” (which are anything but).
In any case, it attempts to set a cookie on your device, so you should never receive it again in that browser for any page on my site. If you are anything like me, you might wish to browse with uBlock greylisting all third party resources on all sites. It works a charm for de-annoying the web when all you want to do is read.