ezcontent-8.x-dev/modules/ezcontent_paragraphs/modules/ezcontent_embed/ezcontent_embed.module

<?php

/**
 * @file
 * Module file for ezcontent_demo.
 */

/**
 * Implements hook_preprocess_HOOK().
 */
function ezcontent_embed_preprocess_paragraph__embed(&$variables) {
  $variables['#attached']['library'][] = 'ezcontent_embed/ezcontent_embed_css';
}

/**
 * Implements hook_preprocess_HOOK().
 */
function ezcontent_embed_preprocess_block(&$vars) {
  if (!empty($vars['elements']['content']['#block_content'])) {
    $bundle = $vars['elements']['content']['#block_content']->bundle();
    if ($bundle === 'embed_block') {
      $vars['#attached']['library'][] = 'ezcontent_embed/ezcontent_embed_css';
    }
  }
}