I have s23 ultra and this started happening when I went on play store to do updates etc......not showing the icon on some apps.....but has seemed to have sorted itself out now.......as for lock screen etc that's always been fine........sorry this doesn't answer your question but you are not alone
Some are like that now, I have a few that do show colours of the app on the lockscreen. Like YouTube is red, I don't use WhatsApp anymore so can't confirm on that icon.
