If I search for 'spam-cleaner'
$this->assertCanonicalUrl($this->buildLink('spam-cleaner', $user));
I found route
<route route_type="public" route_prefix="spam-cleaner" format=":int<user_id,username>/" build_class="XF\Pub\Route\SpamCleaner" build_method="build" controller="XF:SpamCleaner"/>
Why this works:
{{ link('spam-cleaner', $thread) }}
and this does not work?
{{ link('hihihaha', $thread) }}