Hi there,
the Site uses the Header Element:
https://docs.generatepress.com/article/header-element-overview/
If you go to Appearance > Elements you will see a Header Element that is assigned to the Entire Site. In the display rules, add an Exclusion: Blog.
Now make an exact duplicate of that Header Element. Add new and copy over the settings. Or use a Duplicate Post plugin to just copy it.
Then in the Hero content of the header you will see <h1>{{post_title}}</h1>
replace the {{post_title}}
template tag with your new heading e.g <h1>Das Neuste</h1>
Set your display rules to Blog and remove the exclusions.
It is only the Blog page that doesn’t use the {{post_title}} as it doesn’t have one 🙂