add_filter on “the_excerpt” only works when post does not have excerpt

I posted an article about this a while ago:

function wp_trim_all_excerpt($text) {
  // Creates an excerpt if needed; and shortens the manual excerpt as well
  global $post;
  $raw_excerpt = $text;
  if ( '' == $text ) {
    $text = get_the_content('');
    $text = strip_shortcodes( $text );
    $text = apply_filters('the_content', $text);
    $text = str_replace(']]>', ']]>', $text);
  }

  $text = strip_tags($text);
  $excerpt_length = apply_filters('excerpt_length', 55);
  $excerpt_more = apply_filters('excerpt_more', ' ' . '[...]');
  $text = wp_trim_words( $text, $excerpt_length, $excerpt_more );

  return apply_filters('wp_trim_excerpt', $text, $raw_excerpt);
}

remove_filter('get_the_excerpt', 'wp_trim_excerpt');
add_filter('get_the_excerpt', 'wp_trim_all_excerpt');