This stopped working for me recently. Don't believe I did any recent updates but not sure. Here is the output
PS C:\Program Files> .\LG-UltraFine-Brightness-Control\LG-Ultrafine-Brightness.exe
Unhandled Exception: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at hid_get_feature_report(hid_device_* , Byte* , UInt64 )
at get_brightness(hid_device_* handle)
at LGUltrafineBrightness.mainForm..ctor()
at main(String[] args)
at mainCRTStartupStrArray(String[] arguments)