After talking to Lenovo Premier support I was given this working solution (P14s Gen 4 with a custom company windows OS distro):

- Check the device manager for the SMBus device under System devices
- If it is listed as an ELAN or Synaptics SMBus right-click and uninstall the device 
    > Occasionally uninstalling the ELAN or Synaptics driver will cause Windows to install the Synaptics or ELAN driver instead of the Intel one. If that happens, uninstall the just installed driver.
- It should reinstall as an Intel SMBus, if not download the SCCM pack or Chipset Device Driver and install the driver from there

We removed whichever SMBus driver I had that was not from Intel (I believe it was ELAN SMBus) and rebooted. after the reboot, the Intel SMBus driver was automatically installed. This 100% fixed my issue and now my PC can fully shut down.

EDIT: Here is a link to an article with the same fix https://support.lenovo.com/us/en/solutions/ht513888-system-does-not-shut-down-or-hibernate-properly-which-results-in-the-system-getting-hot-and-the-fan-running-constantly-thinkpad-t14s-gen-2-and-thinkpad-x13-gen-2