I know it‘s not a classic flap but I have the zippy coin purse in a 25 series and it‘s indeed extremely shiny and glossy! I also compared it to my Chanel Mini which has a more matte caviar leather (that one is a 23 series).
I'm not sure if there is a difference in Chanel between their bags and their SLGs when it come to the different series and leathers.. but I thought I'd show it anyway to compare