Note: If you are reading this for the fist time, you may jump directly to the UPDATE, since it addresses the issue more accurately.
So I got a
Use image preloading capabilities through rel="preload" attribute
The as attribute indicates the kind of object the browser should expect. So this adds highest priorities among all images you load on page, but not change priority "JS -> Image"
Declaration without as allow to preload images even before js load, increasing Image loading priority.
Preloading feature