Remove attributes

Proof of concept – this code alters exactly as above, and it works just as before except its less code in the DOM. The inline CSS ended up optimized a bit further.

function img_attr_cleanup(){
add_filter("wp_get_attachment_image_attributes",function($attributes){

    if (isset($attributes["data-dominant-color"])){
        unset($attributes["data-dominant-color"]);
    }
    if (isset($attributes["data-has-transparency"])){
        unset($attributes["data-has-transparency"]);
    }

    return $attributes;
});
}
add_action("template_redirect", "img_attr_cleanup");

add_action("wp_enqueue_scripts",function(){
 wp_dequeue_style("dominant-color-styles");

 wp_register_style('dcs',false);
 wp_enqueue_style('dcs');
 wp_add_inline_style('dcs','img:not(.has-transparency){background:var(--dominant-color)}');

},20);