Update: I found a setting to disable this now in Configuration > General > Theme, Scripts & Custom CSS. Still think that it’s truly bizarre default behavior.
It’s also completely unclear from the settings what function this random variety of frameworks and libraries serves, why I should want to include them on every page of my website slowing everything down and causing conflicts, or what the consequences of turning them off might be (did it break some other corner of the plugin now?).
Thanks for your comment and I’m happy to hear you figured out what caused this. I assure you that our plugin is being maintained. You can look at our changelog on our website to see the number of updates we launch per year: https://tribulant.com/docs/wordpress-mailing-list-plugin/31/#doc6 (see Release Notes).
I can see your frustration with how confusing that setting is. I do agree with you. It’s from the past and it’s necessary to have it, as you now know. I’ll add a note so that we can work on this and see how we can clarify that whole section. We don’t know for when or which version, but I have added it now to our list.
It should only affect the CSS and such of your page and not break a part of our Newsletter plugin. You can still edit the CSS on your own.
For most themes, it works without configuring that part when you first install our plugin. But, since there are dozens of thousands of themes, and we can’t support them all, we offer a few settings to help with this.