The 2nd article goes into more details

“Ultra-processing degrades the internal structure or “food matrix,” the complex internal structure that not only holds the corn together, but influences the bio-availability of the nutrients, how our bodies use the food and whether we feel full after eating it.”
…
“But the process also appears to accelerate the speed at which our digestive tracts absorb glucose and other nutrients from food, causing greater spikes in blood sugar and insulin levels, studies show.”
…
““Extrusion cooking at very drastic pressures and temperatures is a kind of predigestion of your food,” said Anthony Fardet, a nutrition scientist at the French National Institute for Agriculture, Food, and Environment who studies the effects of food processing on health.”
Source

I also agree that a study of 20 adults is absurd.