There are issues that you get with GraphQL that are generally much easier to solve with REST, though. While it's easy to set up a GraphQL API that technically makes your whole graph available, going off of your default resolver functions alone is going to cause serious performance issues as soon as queries start to get more complex. The default behavior is basically n+1. To fix that, you have to do query introspection, which is significantly more complicated than just having a dedicated endpoint. Depending on your data sources & how easy it is to cache, this can be more or less of a problem.

This isn't to say that GraphQL is bad or anything, but there are definitely some gotchas that are important to evaluate before diving in.