TypeScript enums not properly inlined

Currently running a fairly simple build script from [one of my package](https://github.com/mgcrea/pino-pretty-compact/blob/v1.1.2/package.json#L28), basically:

`tsup --entry src/index.ts --format cjs,esm --no-splitting --sourcemap --dts --clean --entry src/bin/cli.ts`

Unfortunately it does not properly inline the following enum: https://github.com/mgcrea/pino-pretty-compact/blob/v1.1.2/src/prettifier.ts#L56

It's currently manually inlined (for release) but just replace the number with the enum to test and rebuild.

Tried to remove all CLI options, but no more luck, it does not inline the enum (`tsc` works).

Any idea?