Kint as dumper does not render the kint-php/resources/compiled/ CSS & JS files to actually run

Problem/Motivation

In Devel 4+ in drupal 9, using Kint as the dumper the CSS and JS files are not being loaded.

/vendor/kint-php/kint/resources/compiled/original.css /vendor/kint-php/kint/resources/compiled/shared.js /vendor/kint-php/kint/resources/compiled/rich.js

In Drupal\devel\Twig\Extension\Debug::dump() if I change

    return ob_get_clean();

to

    var_dump(ob_get_clean());
    die();

I can see the inline CSS and JS is there. I can see the 'is_safe' in the Twig function declarations, so I cannot see why the CSS and JS is being stripped when doing even something as simple as this in any twig template in the theme.

{{ kint('hello') }}

Hoping someone can suggest where this is going wrong. I could not see anything in the readme or existing in the issue queue.

Proposed resolution

Unknown.