Lazysizes 2 is here
It claims to be even faster and brings a new plugin that polyfills object-fit and object-position. This allows for easy arrangement of e.g. images and videos inside containers.
As caniuse.com puts it, object-fit/object-position is a:
Method of specifying how an object (image or video) should fit inside its box. object-fit options include "contain" (fit according to aspect ratio), "fill" (stretches object to fill) and "cover" (overflows box but maintains ratio), where object-position allows the object to be repositioned like background-image does.