Then, I wonder if LZ thinks that under the yellow light, the red balloon will only reflect the red light, so that the black balloon you see will not reflect light. In fact, all the examples in our physics are purely theoretical. Because the surface of the balloon is smooth, it will reflect the light shining on it (that is, yellow light) to a greater extent, so you will find that the balloon is "yellow"

I hope my answer is helpful to you.