This is a BUG of P3D which considers Summer + Day conditions as night. You may observe this problem in the P3D main menu when selecting your Time and Season.
It seems to be related to only a few days in June.
This won’t cause any issues besides lights appearing during the day.
It was reported to the Lockheed Martin team and we hope this will get fixed soon. The error is related to P3D timezones.