In reply to Lukasz.

I imagine this is a js based lazy load, whereas the wp core lazy load simply adds the new, somewhat experimental loading=”lazy” attribute to images (and iframes too now iirc)

Honestly, I kinda prefer the the html attributes since it doesn’t rely on an external script, I wonder if the reasoning for the js method is because it has wider support? My opinion is, that something like this falls under the umbrella of progressive enhancement.