Thanks for reading this.
When rendering I get black areas using Cycles. It happens with path tracing and also branch tracing. I tried to deactivate all different light sources but problem still persists. I have checked the geometry and that seems OK too.
Blender version 2.92
I have included the blend file in the following link.
https://drive.google.com/file/d/10B9H-IZI_4YW23S_orMQxuBohhXw6plb/view?usp=sharing
Thank you very much for helping out.