Custom Shortcode not working in own pattern

Hello,

I created a custom shortcode that I have been using on my site for a while now (code in functions.php, then use Shortcode block on template or page).

Now I wanted to move both this shortcode and an icon into a custom pattern in order to reuse this construction on a couple of templates. For some reason the shortcode is not rendered inside this pattern. It shows it verbatim “[back_button]” instead of rendering the button.

Is that a bug or a feature? Are shortcodes supposed to work in patterns at all?

(Just for clarity, since I use the German translation which is confusing: Using the term “pattern” I mean the purple-coloured thing.)