It's amazing how this one experience will not only make me never go to a Sam's club again (after getting the replacement note) but also actively dissuade others from joining Sam's club. All they have to do is provide us updates!
So is Corning just lying? Page 2 of their GG5 datasheet shows similar hardness to GG4: https://www.corning.com/content/dam/corning/microsites/csm/gorillaglass/PI_Sheets/Corning%20Gorilla%20Glass%205%20PI%20Sheet.pdf