Seeing something in a new light or a different light is a figure of speech that means the subject is perceived with different face or complexion due to the shift in contextual frame, circumstances, or additional factors. But there is a literal meaning to this expression, too.
The play of shadows, the angle, intensity, and temperature of the light affects the viewing experience and emotional response or resonance to the subject. Is the ability to infer meaning from the quality of light specially tuned to primate visual cortex (up to 25% of brain volume among present-day humans), or do other vertebrates also have emotional response to the character of light they see? It is not uncommon in the elementary grades for teachers to cover the overhead banks of fluorescent lights with fabric or paper to affect the color of the light and the amount of light. A more dramatic non-verbal signal to young students to hush comes from turning off the room lights.
So “seeing it in a new light” means reconsidering or seeing all-over again with fresh eyes the things one faces. And so the next time a problem seems unsolvable or subject seems dull or flat, then alter the lighting (literally or in the figurative sense of shifting its contextual frame, the color and angle and temperature and amount of illumination.