Next.js のドキュメントには次のように記載されてる React will automatically cache fetch requests with the same input in a temporary cache. This is an optimization to avoid the same data being fetched more than once during a rendering pass - and is especially useful when multiple components need to fetch the same data. React が自動的に fetch request をキャッシュすると書いてある。
![React がネイティブの fetch を patch しようとしてる話](https://cdn-ak-scissors.b.st-hatena.com/image/square/51d0e17361da2d7baf9963de7f1f3d970bfa4431/height=288;version=1;width=512/https%3A%2F%2Fstorage.googleapis.com%2Fzenn-user-upload%2Favatar%2F0ed964c63f.jpeg)