So I'm taking a look, but the setup is incredibly complex. I don't know exactly how they're pulling off their approach here. They have a hash in their src attribute, and they have a bunch of custom properties in their elements. Like:
<img src="#" v-responsive="media.src" v-bind:alt="media.alt ? media.alt : product.title" >
This is an accepted solution.
Holy shit I figured it out. I don't know if whatever I did is the most effective way of changing that, but I was able to get it done. Apparently your theme is using Vue.js, of which I know absolutely nothing about. But I was able to just use some reasoning based on what I was looking at and looking at some of their docs to at least pull the biggest image in your file. It may not be the correct way, but it's the best I can do not knowing what's going on exactly. Go ahead and preview the Ninthony Editing theme and make sure everything looks ok to you and then publish whenever you feel like it.
The second and third picture on the page are really blurry on my end. Same as the product picture was.
I need to zoom in a bit to see the blurry effect better.
Some strange side note: the third picture with the marked circle was sometimes sharp and sometimes blurry. And not that I was aware of changing anything in between. (Maybe unknowingly by trying, that could be)