thinkbook 16p gen4 owner here, also had the same problems with random hanging at reboot/shutdown, when running pacman, and at random times every few hours. Switched to nvidia-open-dkms and have been stable ever since - i did run into problems with nvidia-inst -o flatly ignoring my request to use the open driver and installing nvidia-dkms anyway so had to put it on separately
one thing to be aware of, as i understand it the “open” drivers are missing support for CUDA which may or may not be a problem for your use case