Hi Hans Gunter,
Thank you for posting in Microsoft Community.
The Surface Book 3 does not have a Thunderbolt 4 port; Therefore, you cannot use a Thunderbolt 4 docking station with your Surface Book 3. But it does have a USB-C port that supports dual 4K displays at 60Hz. You can use the Surface Dock 2, which supports dual 4K displays at 60Hz and is specifically designed for Surface devices. For more details on its specification see Surface Dock 2 overview - Surface | Microsoft Learn.
For troubleshooting guide, see Troubleshoot connecting Surface to an external display - Microsoft Support.
I hope this answers your confusion.
Kind regards,
Lavenia