Disable in specific posts – Gallery post

Hi Jad,

Sorry for the late replay, I was on holiday.

There are filters which you can use to make exceptions.
Example:

function dfi_skip_page ( $dfi_id, $post_id ) {
  if ( $post_id == 23 ) {
    return 0; // invalid id
  }
  return $dfi_id; // the original featured image id
}
add_filter( 'dfi_thumbnail_id', 'dfi_skip_page', 10 , 2 );

I suggest you check for the shortcode with has_shortcode.

Untested example:

function dfi_skip_gallery ( $dfi_id, $post_id ) {
  $post = get_post($post_id);
  if ( has_shortcode( $post->post_content, 'gallery' ) ) {
    return 0; // invalid id
  }
  return $dfi_id; // the original featured image id
}
add_filter( 'dfi_thumbnail_id', 'dfi_skip_gallery', 10 , 2 );

You second post should be possible to do with the same filter. With different checks.

Let me know how it went.