Most apps are simple, don’t need to send much data around if you don’t put 3-10 user tracker in, and Rest is just really, really simple for most parts.
In every project I worked so far that used GraphQL, developers tend to not care about backwards compatibility of APIs because having tons of optional properties in query responses doesn’t feel nice.
As always, there are exceptions and if it makes sense, sure, go ahead. But be aware of the dependencies and the magic you get into your project. Oh, and don’t use it for file upload, that’s just painful.