I could not find a class to only blur the image but I managed to blur the whole item using the code below, which works for me.
.arc-post-css-blurred {
filter: blur(0.5rem);
}
I only noticed that when someone clicks on the blurred “quick view” button, which appears on hover, it will still show the original image of the restricted item.
Here you can view it: https://pornprint.com/