Hello. You did not present the photos to which the question refers, which makes it impossible for your question to be answered. However, I will try to help you in the best possible way.
Your question informs us that the photos are of a star-forming molecular cloud. The molecular cloud has dust, especially when the star is forming. In this case, we must keep in mind that in photos taken in visible light, the dust is able to appear, especially in space, where this dust would not reflect light, unlike the star in formation. In this case, we can conclude that in the case of the photo taken in visible light, we could see the molecular cloud as a dark spot, due to the dust. However, it would not be possible to view it in a photo taken with infrared light.
