Sorry I don’t really have any more detail. I read this blurb about a book on either reddit or goodreads. Something about humanity discovering interstellar travel or something major like that and aliens sending a message warning humanity to stop, or else. At least that’s what I remember. Any help would be appreciated. Been searching for a couple of hours and have had no luck.
I think there was something along those lines in this PBS Space time video. Maybe they mention the book or it’s mentioned in the comments.