Reproduction link or steps

1. Go to: https://github.com/ianzone/tsdown-bug
2. /build is generated by pnpm run build, and /dist is generated by pnpm run prod

What is expected?

named exports should not be renamed, e.g.

export { Obj }

should not be renamed as

export { Obj as Obj$1 }

But in /dist, they are renamed.

What is actually happening?

it will cause js to report missing export xxx

Any additional comments?

I'm doing this PR, and I hope the rollup replacement won't cause any trouble, which means the /dist should work as /build, wish tsdown team could confirm that.