The argument is that it is U.S. companies that are insanely competitive at making high-fructose corn syrup, and that the EU has largely banned it as a shield to European companies making other sweeteners (e.g.: sugar).

I would argue that the ban on genetically modified organisms (GMO) is a cleaner example of European protectionism (not that all other countries, the U.S. included, do not also practice protectionism).

You can find lots of sources for the fact of this near-ban, but this one is nice and pointed: "Because of its low cost and long shelf-life, HFCS is used widely in manufacturing many food products, including candy, throughout the United States. However, due to strict EU regulations, HFCS is banned in much of Europe" https://www.sugarjoy.com/pages/hfcs-gmos-and-trans-fats

The whole reason soda tastes better outside the US is because bottlers in most other countries still use real sugar. HFCS is cheaper in the US because we heavily subsidize corn production for some reason.

So it seems weird to me that people would complain that the EU made it harder for Coca-Cola to make their product taste shittier. There is a reason there is a huge market for "Mexican Coke" throughout the US.