My previous project involved complex data in a graph DB, and twice we considered if maybe we should use GraphQL. After looking into it, we decided to stick with REST, because it's easier, we're the only ones using our backend, and all our responses are highly customised for what we're going to use it for. GraphQL would be a lot of extra work for no real gain; maybe we would end up with somewhat less highly customised hard-coded Cypher queries, but then we'd have to figure out how to represent them in GraphQL and translate that to the queries we'd need, and that was not going to be trivial.
In my current project, other people made the opposite decision: they do use GraphQL for a fairly similar use case, and they regret it. It works, but it complicates things for fairly little gain. REST would have worked just as well.