How do I add a link to the #title property of a checkbox?
The code is not calling $this-&gt;t() passing the correct arguments. The correct code would be the following one.

$pane_form['cgv'] = [
  '#type' =&gt; 'checkbox',
  '#default_value' =&gt; FALSE,
  '#title' =&gt; $this-&gt;t('I have read and accept &lt;a href=":general-terms"&gt;the general terms and conditions of business&lt;/a&gt;', [':general-terms' =&gt; Url::fromRoute('entity.node.canonical', ['node' =&gt; 1], ['attributes' =&gt; ['target' =&gt; '_blank']])-&gt;toString()]),
  '#required' =&gt; TRUE,
  '#weight' =&gt; $this-&gt;getWeight(),
];