Style ACF fields as deprecated

Admin.php

class Admin
{
  public function __construct()
  {
    add_action('admin_enqueue_scripts', [$this, 'acfDeprecationStyles'], 10, 2);
  }

  public function acfDeprecationStyles()
  {
    echo '<style type="text/css">';
    echo $this->generateAcfDeprecationStylings();
    echo '</style>';
  }

  private function generateAcfDeprecationStylings()
  {
    $style = '';
    $style .= '.acf-field.deprecated {
      opacity: .8;
    }';

    $style .= '.acf-field.deprecated .acf-label label {
      color: red;
    }';

    return $style;
  }
}

Simply add deprecated to the class setting in the ACF field (in the admin) and the field will be shown red and a bit transparent for the user.