Force Yoast SEO to show the default open graph image in case a feature image isn't set.

disable-yoast-seo-automatic-og-image-lookup.php

<?php

/**
 * Plugin Name: Disable Yoast SEO Automatic Open Graph Images
 * Plugin URI: https://gist.github.com/jakebellacera/c2aab8f786a0617b27dd4914c70463d4
 * Description: Shows the default open graph image in case a feature image isn't set, rather than showing a random image on the page.
 * Version: 0.0.0
 * Author: Jake Bellacera
 * Author URI: https://www.jakebellacera.com/
 */

/**
 * Force default open graph images in case feature image isn't set
 */

add_filter('wpseo_add_opengraph_images', 'jb_force_default_open_graph_image', 10, 1);
function jb_force_default_open_graph_image($images) {  
  if (!has_post_thumbnail() && WPSEO_Options) {
	  $default_id = WPSEO_Options::get('og_default_image_id', '');
	  
	  if ($default_id) {
		$images->add_image_by_id($default_id);
	  }
  }

  return $images;
}