Find Unused Shortcodes in WordPress with Code | https://www.ibenic.com/unused-shortcodes-wordpress-code

admin_init.php

<?php

add_action( 'admin_init', 'ibenic_get_all_posts_shortcodes' );

function ibenic_get_all_posts_shortcodes() {
  if( isset( $_REQUEST['get_shortcodes'] ) ) {
      // Our code will go here
      die();
  }
}

display.php

<?php

// This goes outside the query loop
echo 'Possible Unused Shortcodes<br/>';
if( $posts ) {
    echo '<ul>';
    foreach ($posts as $unused) {
        echo '<li>';
          // Admin URL so we can edit it immediately
          echo '<a href="' . admin_url( 'post.php?post=' . $unused['id'] . '&action=edit' ) . '" >';
          echo $unused['link'] . '</a>';
          // Showing the possible unused shortcode
          echo ' - ' . $unused['shortcode'];
        echo '</li>'; 
    }
    echo '</ul>';
} else {
    echo 'No unused shortcodes. Good Work!';
}

query.php

<?php

$args = array(
  //Type & Status Parameters
  'post_type'   => array( 'post', 'page' ),
  'post_status' => 'any',

  //Pagination Parameters
  'posts_per_page'         => -1,
);

// In case we have a huge Database
set_time_limit(0);

$query = new WP_Query( $args );
$posts = array();

if( $query->have_posts() ) {
  while( $query->have_posts() ) {
    $query->the_post();
    // Getting the content and checking for unused shortcodes
    // Code inside query loop will go here...
  }
  wp_reset_postdata();
}

// Code outside query goes here

shortcode.php

<?php
// This goes inside the query loop
ob_start();

the_content();
// Getting the parsed content 
// where all registered shortcodes have been replaced
$output =  ob_get_clean();

// Checking for a shortcode pattern
preg_match_all( '@\[([^<>&/\[\]\x00-\x20=]++)@', $output, $matches );
// If any match, add it to array
if( $matches[0] ) {
  $posts[] = array( 
    'id' => get_the_id(), 
    'link' => get_permalink(), 
    'shortcode' => $matches[1][0] );
}