When is GraphQL actually better than REST for internal APIs?

We've used REST for nearly all our internal service stuff, and it works. But I keep hearing about GraphQL, even for services talking to each other. It just seems like a lot more complicated than it needs to be, especially since we manage both sides. I mean, where does GraphQL actually shine over REST for internal services? Like, for pulling together data, or when things change, or updating what data looks like? I'm just trying to see if it's worth even thinking about for new projects or if we should just stick with what's working.