Originally, grenadine was syrup flavoured with pomegranate. Sadly, most of today's commercially available grenadine syrups are flavoured with red berries...
I just noticed this comment from Jeff from about a week ago: "This is an old recipe from before I made all of my syrups 2:1. What we do now is combine the pomegranate juice, orange flower water, and pomegranate molasses, and then use the Universal Syrup Calculator to make a perfect 2:1 grenadine at the bar." Page for his calculator: https://jeffreymorgenthaler.com/universal-syrup-calculator/ And someone turned it into a web form: https://www.syrupcalc.com/