Craft CMS 5 - display related entries on a 'Used by' tab, using a custom template UI element

relatedEntries.twig

{% set rels = craft.entries.relatedTo({ targetElement: element }).siteId('*').collect() %}
{% set owners = [] %}

{% for rel in rels %}
    {% set owner = rel.owner ?? rel %}
    {% set owner = owner.primaryOwner ?? owner %}
    {% if owner.canonicalId not in owners %}
        {% set owners = owners + {
            (""~owner.canonicalId~"") : {
                cpEditUrl : owner.cpEditUrl,
                title : owner.title,
                site: owner.site.name,
                section: owner.section.name,
                canSave: owner.canSave(currentUser)
            }
        } %}
    {% endif %}
{% endfor %}

<div class="pane">
    {% if owners|length %}
        <h2>This content is used by the following entr{{ owners|length == 1 ? 'y' : 'ies' }}:</h2>
        <ul style="list-style: square; margin-left: 1rem;">
            {% for item in owners|sort((a, b) => a.title <=> b.title) %}
                <li>
                    {% if item.canSave %}
                        <a href="{{ item.cpEditUrl }}">
                            {{ item.title }}
                        </a>
                    {% else %}
                        {{ item.title }}
                    {% endif %}
                    ({{ item.site }} ▸ {{ item.section }})
                </li>
            {% endfor %}
        </ul>
    {% else %}
        <h2>This content appears to be unused by any entries at the moment</h2>
    {% endif %}

</div>