I found out that the cause of this error is dts plugin's compilerOptions.baseUrl option.
when I set baseUrl to .. it will work fine

I don't understand why tsup is setting it to absolute path

Version

tsup: latest
typescript: latest

Repro

https://github.com/Dunqing/unplugin-moment-to-dayjs

set tsconfig's baseUrl to . or remove it and execute pnpm run build.
you will see the error.