You have some plugin which receive start part of your article and create keyword
"@context": "
schema.org",
"@type": "Article",
"headline": "Alu-Verkleidung",
"inLanguage": "de-DE",
"author": "Super User",
.....
But you in start part of article - added OrdaSoft
Joomla gallery shortcode, and next our Joomla gallery plugin found this "Joomla Gallery shortcode" and replace it to gallery, But because insert do in some keywords info - insert do incorrect - and you see some code from image gallery
We will be happy if you help us too and you put excellent review and 100 hits
on Joomla.org for our Responsive gallery
extensions.joomla.org/extension/os-responsive-image-gallery
If you would like any further information or need some customization service,
please do not hesitate to contact us too.
Best Regards,
OrdaSoft team