cannot use kebab-case keys from `.json` file default exports

[alexzhang1030]

Environment

stackblitz unbuild: ^1.1.1 node: 16.14.2

Reproduction

https://stackblitz.com/edit/node-z61fts?file=index.js

Describe the bug

When import a kabab-case field from json file.

The result after the build is incorrect.

Please see reproduction and execute npm run build, and see dist/index.js.mjs.

I think this is an upstream error from rollup. But I cannot reproduce it by using rollup.

Additional context

No response

Logs

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