They are experimenting with carbonation to get an optimal balance of appealing and healthy. What a lot of people don't know, don't care, or are confused about due to the big soda sellers defending their profits, is that the higher the carbonation goes the lower the PH goes until you're just as acidic as any other soda out there.

If that's the case, you might as well take any diet soda sweetened with a sugar alternative known to be safe or healthier than sugar, and infuse it with CBD. They are trying to stay above that on the "good for you" scale. Lightly carbonated is probably where they'll settle, and consistency will follow.