The breadcrumb template breadcrumb.html.twig does not contain updated classes and other markup from USWDS v3.
See https://designsystem.digital.gov/components/breadcrumb/.
Update the template file according to USWDS docs -- specifically, adding a <nav> tag as a wrapper and updating classes on the elements:
{% if breadcrumb %}
<h2 id="system-breadcrumb" class="visually-hidden">{{ 'Breadcrumb'|t }}</h2>
<nav class="usa-breadcrumb" aria-label="Breadcrumbs,,">
<ol class="usa-breadcrumb__list">
{% for item in breadcrumb %}
<li class="usa-breadcrumb__list-item">
{% if item.url %}
<a href="{{ item.url }}" class="usa-breadcrumb__link">{{ item.text }}</a>
{% else %}
{{ item.text }}
{% endif %}
</li>
{% endfor %}
</ol>
</nav>
{% endif %}Active
3.1
Code
Removed old USWDS v1 (or v2?) CSS. The newer versions of the crumbs look good without it.