Scss support with esbuild's sassPlugin

I am trying to use styleInject property in tsup's config. The problem is that it seems not to work due to the sass plugin for esbuild. The plugin generates an index.css file with all of the css contained in the scss files.
For some reason though, the styleInject may run after the plugin's compliations which causes the styleInject to not have any effect.

The plugin's npm package is called `esbuild-sass-plugin`.