[Gregordinary]

Besides Tab, Diet Coke from a fountain contains saccharin: https://www.foodnavigator.com/Article/2008/04/17/Coca-Cola-w...

(Trying to find another source, I believe Diet Pepsi from a fountain does as well, to extend shelf life.)

[therein]

Wow that blows my mind. No wonder soda from fountain tastes different, and I am not even talking about only the low-calorie ones. I thought it was merely due to some sort of imprecision in dispensing the concentrate.