Issues with html code in api answer

I am using the Gutenberg Block and try to fetch the data in rendered node. My template is very simple: {rendered:html}

But the plugin outputs this:

<div class="&quot;wp-block-columns"><div class="&quot;wp-block-column"><div class="&quot;wp-block-columns"><div class="&quot;wp-block-column"><figure class="&quot;wp-block-image"><img decoding="async" src="//almgrill.de/wp-content/uploads/2026/07/neue-Karten-Pfifferlinge-pdf-543x768.jpg&quot;" alt="&quot;Vorschau" /></figure></div>…

as you can see it inserts kind of encoded quotes in class, alt and src attribute and strips out classes in general. The first div should contain “wp-block-columns is-layout-flex wp-container-core-columns-is-layout-995f960e wp-block-columns-is-layout-flex” but only “wp-block-columns” is rendered?!