Just leaving this here in case it helps somebody:
Like probably a few people, I tried FS2020 with a slightly under powered machine, and unsurprisingly got poor results. But after upgrading my hardware (not including the drive) I found I was getting error code 0x803F8001 on starting the game. This seems like it's purely down to Windows activation following a hardware upgrade. You can try navigating to Settings --> Update & Security --> Activation, and using the reactivation options there. Good Luck!
