They use a different lighting system compared to routes released in tsw3 or improved like riesa dresden which causes weird lighting issues to appear.
Yeah I noticed this on the Spirit of Steam route for PC on Steam which was originally for TSW2, then got updated to TSW3. These weird balls of light appear in multiple light source places on the route during foggy weather. I did submit a support ticket about it as it's the only route I've noticed it on so far.