I use the below to add custom html or a text in WooCommerce single product pages, after short description:
function my_content( $content ) {
$content .= '<div class="custom_content">Custom content!</div>';
return $content;
}
add_filter('woocommerce_short_description', 'my_content', 10, 2);
How to restrict this on product pages that contain a specific product tag (not a product category)?