If you are using ESLint 9's Flat Config, please configure it like this:

import { flatConfig as pluginNext } from '@next/eslint-plugin-next';

export default [
    // ...
    pluginNext.coreWebVitals,
    // ...
];

Why write it this way? Take a look at the @next/eslint-plugin-next source code. It's very easy to understand.