Hello Martin,
Welcome to Microsoft Community.
After reading everything you've posted here in full, I notice that you've made some efforts to try to fix the issue, such as trying to uninstall the touch screen driver in the Device Manager and then restarting your Surface. During the reboot, the Surface redeploys the driver, so after entering the system normally, the touch screen is fine.
But when you turn off the device normally and start it up while using it here, you notice that the touch screen function fails again. Since it works fine in UEFI, this leads me to speculate that the problem may still be coming from the driver, or from the system level. Please try manually downloading and reinstalling the driver and firmware package for Surface Book 2:
Download Surface Book 2 Drivers and Firmware from Official Microsoft Download Center ****
After the installation is complete, restart your Surface. At this time, you do not need to calibrate again. Please directly check whether the touch screen malfunction will occur again.
If the problem does not appear after restarting the Surface again, then the problem may have been fixed, please check in the next few days.
But if the problem continues to recur, then the next thing you need to do may be to reset the Surface, so be sure to back up important data in advance. To learn how, see****Restore or reset Surface for Windows and follow the recommended steps for "Reset this PC".
If that doesn't work, my final suggestion is to create a dedicated USB recovery drive for the Surface Book 2 and use it to restore your Surface to factory Settings:
Creating and using a USB recovery drive for Surface - Microsoft Support
Please don't hesitate to let us know the result.
Best Regards,
Mitchell | Microsoft Community Support Specialist