I felt the same way, they used to taste awful to me, now I only notice a slight difference between Dr Pepper zero and regular. Maybe I just got older and my taste buds degraded?

A lot of the “zero” soft drinks are sweetened differently from the “diet” ones. There’s often a mix of different sweeteners so you don’t get too much of any one aftertaste.

The one we’re trying to avoid the most in my household is sucralose. Genotoxicity and upregulating inflammation and oxidative stress are bad things. Accumulating unchanged in the environment and resisting biodegradation is a bad thing.

https://pmc.ncbi.nlm.nih.gov/articles/PMC12251854/

Dr pepper zero doesn't use as much aspartame as dr pepper diet. It uses more of a mix of different sweeteners