When I read Docs about [Electron](https://www.electronjs.org/docs/latest/tutorial/tutorial-preload):
>From Electron 20 onwards, preload scripts are sandboxed by default and no longer have access to a full Node.js environment. Practically, this means that you have a polyfilled require function that only has access to a limited set of APIs.
why there comes a new concept: polyfilled
1.how to understand it(polyfilled)?
2.what's the relationship between polyfilled and limited Electron APIs/Node.js API?