This has the side effect of disabling ES5 builds by default for new projects. To enable ES5 builds and differential loading for browsers that require it (such as IE or UC Browser), simply add the browsers you need to support in the .browserslistrc file.
The Angular Package Format no longer includes ESM5 or FESM5 bundles, saving you 119MB of download and install time when running yarn or npm install for Angular packages and libraries. These formats are no longer needed as any downleveling to support ES5 is done at the end of the build process.
ES5 的 angular 包不用单独下载 npm 了，改为在构建时自动降级。
Default bundle budgets have been reduced by ~75%