Download Nvidia drivers v466.77
https://www.nvidia.com/download/driverResults.aspx/176265/en-us
Uninstall Nvidia drivers and restart PC.
Install 466.77 drivers and restart PC.
Source
https://forums.flightsimulator.com/t/weird-lighting-bug/440787/2
https://forums.flightsimulator.com/t/official-discussion-upcoming-hotfix-announcement/436058/615