Rubbing alcohol on my black plastic side door panels

I was just prepping the surface of my plastic black side door panels to clean it but quickly after drying I noticed this whitish stain and in the light it actually looks like the colors of the rainbow. Does anyone know what this is? How do I remove it safely? The other side didn't seem to be affected by the alcohol, just one side. I tried to use soapy water many times and everytime it dries up it would reappear again. I used some windex also and same thing. It may have helped just a bit but still looks whitish where I was rubbing the alcohol. Not sure if it's just car wax that I already had on there by mistake when waxing a couple months ago and the alcohol is making it turn white or if the alcohol may have actually done some permanent discoloring on the black plastic material?