The artificial sweetener in question is sucralose, sold under the brand name Splenda. Sucralose is 600 times sweeter than sugar and can be found in many baked goods, soda, chewing gum, gelatins, and frozen dairy desserts. A 2020 study showed that Splenda was easily Americans' most preferred sugar substitute, with 51.4% of the population using it. The next popular was Sweet'N Low, which contains saccharin, at 25%.
North Carolina State University researchers looked particularly at sucralose-6-acetate, one of the fat-soluble compounds produced when sucralose is broken down (metabolized) in the body, to determine how it affects the body, particularly DNA. They'd already studied sucralose metabolism back in 2018, which is how they knew about the existence of sucralose-6-acetate.