Right now, the preload scanner will send fetches for script tags regardless of type/language, but the script will not execute when parsed. Often, sites will use these custom tags combined with XHR, resulting in double downloads. By deprecating the fetch, the preload scanner and the parser will have the same semantics, and we will not be initiating fetches for scripts we will not execute. To work around this issue and maintain the fetch, sites should use link preload.
Docs: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/eu57SCNltls https://html.spec.whatwg.org/multipage/scripting.html#prepare-a-script