When Spam Protection is enabled on the developer portal, when using Google Chrome the following warning message appears in the developer console:

A Parser-blocking, cross site (i.e. different eTLD+1) script, https://www.google.com/recaptcha/api/js/recaptcha.js, is invoked via document.write. The network request for this script MAY be blocked by the browser in this or a future page load due to poor network connectivity. If blocked in this page load, it will be confirmed in a subsequent console message.See https://www.chromestatus.com/feature/5718547946799104 for more details.

More information about this warning:
https://developers.google.com/web/updates/2016/08/removing-document-write

Potentially, this may lead to incorrect functionality of the reCaptcha feature. This needs to be investigated, and if it really affects, it needs to be fixed.