Over-Fetching and Under-fetching both are the performance issues that can be solved by using GraphQL. You won't see these problems if you have precisely the right endpoints to give your products exactly the correct data. These problems occur when you have to maintain multiple endpoints to get the exact right data. It has increased the data load, which finally results in a performance issue.
GraphQL resolves this issue because it facilitates you to request the specific data which you want from the server. Here, you can specify what you need in a single request and get the exact result that you need in just one response from the server.
