The lights have a Screen mode which works when something is placed under them. So you see the mess when nothing is under the lights and a good look when your photo is in its place. But no all printing modules work correctly with the blending modes, so you have this mess on the last image. If you printed it on the usual desktop printer, it was expectable. So the easiest, fastest, and best way to solve the problem is to follow Monika's recommendation.
Another way is to select all lights, and change their gradient end stoppers to the same color as a start one (or the nearest on the gradient line) and 0% opacity. In this case, you can change the blending mode to Normal. But I'm not sure that you need so deep editing 🙂
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