I’ve noticed this a few times when the light hits my water bottle right it creates a cool reflection, even on surfaces that don’t seem super reflective. It almost seems more like a colorful shadow than an actual reflection. Unfortunately my camera dimmed the colors a bit, so the yellow on the table isn’t as vibrant as it was in person, but I think it’s still a cool effect. This doesn’t seem to happen, or at least not as noticeably, when there isn’t any water in the bottle.