Shortcodes don’t work in patterns (reusable blocks)

Context: WordPress

I created a Gutenberg group block which includes a headline and a Simple Calendar shortcode. I tested the output and everything worked as expected.

Then I transformed the group block into a pattern (f.k.a. widget) and added this pattern block in another page template using the site editor.

Expected result

The headline and the calendar items from Google Calendar are shown wherever I use the template.

Actual result

The shortcode is shown instead of the calendar entries.

Additional information

JSON of the pattern

{
  "__file": "wp_block",
  "title": "Upcoming events",
  "content": "<!-- wp:group {\"layout\":{\"type\":\"constrained\"}} -->\n<div class=\"wp-block-group\"><!-- wp:heading {\"fontSize\":\"large\"} -->\n<h2 class=\"wp-block-heading has-large-font-size\">Upcoming events</h2>\n<!-- /wp:heading -->\n\n<!-- wp:shortcode -->\n[calendar id=\"268\"]\n<!-- /wp:shortcode --></div>\n<!-- /wp:group -->",
  "syncStatus": ""
}

System information

WordPress
Version: 6.4.3
Locale: de_DE
Timezone: Europe/Berlin
Multisite: No
Permalinks: /%year%/%monthnum%/%day%/%postname%/
WP Memory Limit: 40 MB
WP Debug Mode: keine
Script Debug: keine Active Theme

Theme
Twenty Twenty-Four - 1.0
Child Theme: No
Parent Theme: - Active Plugins

Plugins
Local Google Fonts: 0.22.0
Lightbox for Gallery & Image Block: 1.13
Spectra: 2.12.2
Fonts Plugin | Google Fonts Typography: 3.5.1
Simple Calendar: 3.3.0
Pretty Google Calendar: 1.7.1
Default featured image: 1.7.3
Backup-Migration: 1.4.2 Server Environment

Server Environment
Web Server: Apache/2.4.54 (Debian)
PHP Version: 7.4.30
MySQL Version: 8.0.29
Server Timezone: UTC
Display Errors: No
Memory Limit: 256M
Upload Max Filesize: 2M
Post Max Size: 8M
Max Execution Time: 30
Max Input Vars: 1000
fsockopen: Yes
cURL: 7.74.0
OpenSSL/1.1.1n
SOAP: No
SUHOSIN: No
WP Remote POST: Yes
WP Remote GET: No (401) Client Information