Yes, GraphQL would require fewer round trips than corresponding individual queries via REST, but that logic of mapping a GraphQL query to individual SQL queries

Yes, GraphQL would require fewer round trips than corresponding individual queries via REST, but that logic of mapping a GraphQL query to individual SQL queries from the DB resides in the GraphQL layer. So, the question is how does that overhead compare to the overhead caused by multiple REST api calls? And, in addition, how do the GraphQL layers scale as the GraphQL queries become complicated and larger.