According to the Q&A, to fix the terrain emitting light needs new terrain light data. They can’t get that quickly, but they could make some other adjustments, so they’ve done that. Maybe it will all work when they get updated data and can make other adjutsments, but no timescales on that. I’ll try to find the link to the Q&A for you
EDIT - See this link - 24:04 in the video is the bit about night lighting. This is pre patch 5, so gives an idea of what they were thinking of changing