When an application dynamically import an external library (e.g. await import('marked)), webpack will automatically produce a chunk. Setting singleBundle to true has no effect on those kinds of chunks. To disable the creation of those chunks and creating a true single bundle we must set output.asyncChunks to false in the webpack configuration (the documentation on these is not that verbose unfortunately https://webpack.js.org/configuration/output/#outputasyncchunks).

For now, on some project I own, I use the extraWebpackConfig to set it from an external webpack.config.js file, but I think the behavior should be included directly in ngx-build-plus. I am willing to provide a PR if you agree. Let me know.