has_shortcode for content material added after the content material

I added some shortcode after the content material utilizing filter, like this:

add_filter( 'the_content', 'image_posts' );

however now that I run has_shortcode in one other operate, this returns false despite the fact that the shortcode is there (which was added utilizing the above filter.

add_action( 'wp_head', 'gallery_style');
operate gallery_style(){
  if ( has_shortcode( $content material, 'gallery' ) ) {
     // enqueue fashion
     // it fails for posts which add gallery utilizing the_content
  }

how can I take a look at the has_shortcode for contents added utilizing add_filter?