I think it is the other way around. REST inherently only offers, what routes you implement, nothing more. In that sense it is "safe". There are frameworks like "Rocket" in Rust, which make things typesafe from the moment a request arrives at your route's handler. While GraphQL requires you to implement who can access what, because you allow the frontend a lot of freedom to formulate queries. This is inherently unsafe.

Perhaps we are talking about different kinds of "safety" or "aspects of safety"?