Liu Cixin's Dark Forest theory is a pretty dumb take, honestly. Just look at Earth — different species don't constantly try to wipe each other out. Sure, it happens sometimes, but it's actually relatively rare, and a lot of the time extinction isn't even intentional. Like, a huge chunk of Native American deaths came from disease, not deliberate extermination.
At the end of the day, Liu Cixin is basically a social darwinist who's got a thing for authoritarianism, and it bleeds through pretty heavily into his work. Dude is massively overrated imo.
I think the book specifically and explicitly covered the "dark forest doesn't apply when species are near one another" angle.