This has been my experience when integrating with a vendor's APIs where they've been bit by the GraphQL bug. They have a full featured, stable and easy to use REST API, and then a poorly implemented GraphQL solution that doesn't cover all the use cases of the original API, and new features only appear in the GraphQL schema, so you have to be stuck using both and it's a horrible experience.

I'm also not personally a fan of having my API queries on the frontend span multiple lines for things that with a good REST design with OpenAPI are a single method call, but all too often the calls I would need to make to the vendor's GraphQL API were exactly this: did not make use of any of GraphQL's query features, and were effectively just RPC calls.