Z-Image Base 6B: Strange image artefacts

I`ve most time strange artefacts in the image, even with standard settings and promt. Is there a way to get rid of this?
Turbo model does not show this behavior.

<img width="1024" height="1024" alt="Image" src="https://github.com/user-attachments/assets/2a25f8b1-c608-4bf9-8388-815a776ee186" />