Answer:
Please clear your browser cache. Then only the following currently valid map should appear:
For this, enter "clear cache *your browser*" in the search engine and follow the instructions.
The footer shows you the current source. There, you will find the source "Seismic Zones and Subsoil Classes 2017‑07‑20", which was published as an Excel file by DIBt. These are available under "Technical Building Regulations".
