I'm currently experiencing this warning pointing at an unnamed object in a config file, and naming it doesn't resolve the warning. Below is the detailed warning and examples.

Warning:

Anonymous arrow functions cause Fast Refresh to not preserve local component state.
Please add a name to your function, for example:

Before
export default () => <div />;

After
const Named = () => <div />;
export default Named;

Before:

export const = {
  apiUrl: process.env.NEXT_PUBLIC_API_URL as string,
  commitRef: process.env.NEXT_PUBLIC_VERCEL_GIT_COMMIT_REF as string,
  ldSdkKey: process.env.NEXT_PUBLIC_LD_SDK_KEY as string,
  imgixBaseUrl: process.env.NEXT_PUBLIC_IMGIX_BASE_URL as string,
  imgixApiKey: process.env.NEXT_PUBLIC_IMGIX_API_KEY as string,
  imgixResourceID: process.env.NEXT_PUBLIC_IMGIX_RESOURCE_ID as string,
};

Attempted Resolution ./src/config.ts:

const AppConfig = {
  apiUrl: process.env.NEXT_PUBLIC_API_URL as string,
  commitRef: process.env.NEXT_PUBLIC_VERCEL_GIT_COMMIT_REF as string,
  ldSdkKey: process.env.NEXT_PUBLIC_LD_SDK_KEY as string,
  imgixBaseUrl: process.env.NEXT_PUBLIC_IMGIX_BASE_URL as string,
  imgixApiKey: process.env.NEXT_PUBLIC_IMGIX_API_KEY as string,
  imgixResourceID: process.env.NEXT_PUBLIC_IMGIX_RESOURCE_ID as string,
};

export default AppConfig;

Hopefully someone else has experienced this and found a resolution.