Happening to me to me too.
Latest version of AMD Radeon Drivers did not fix it.
Windows 10 1903 build 18362.418
Ryzen X2700
Radeon Vega64
Application logs are clear, no errors listed. The system log shows the reboot error but there isn't anything else that corresponds with the reboot.
I have a repeatable pattern, the reboots happen like this -
Wake PC from sleep OR start PC from powered off OR come back to an idle PC after a break and start The Outer Worlds. Game starts great, loads continue or save without issue. Then, one of two things happens. Behavior 1- when I go to move the mouse or move my character forward the system reboots OR 2- the game is stable and working UNTIL I fast travel somewhere. Once the fast travel is done, the system reboots. Once the reboot is finished and I start the game again it runs stable without issue for hours. The reboot only happens if I quit the game and come back after a moderate amount of time.