lazy load wordpress content images

functions.php

function add_lazy_loading_to_images($content) {
    // Add loading="lazy" to all <img> tags in the content
    $content = preg_replace('/<img(.*?)src=(["\'])(.*?)\2(.*?)>/i', '<img$1loading="lazy" src=$2$3$2$4>', $content);

    return $content;
}

add_filter('the_content', 'add_lazy_loading_to_images');