Correlation != causation. Your correlation can identify a hugely important effect without pinpointing its mechanism. In this case: I think it's very likely that ultraprocessing has not-very-much to do with food health, but UPF foods tend to be hyperpalatable and low-satiety, which almost certainly does. The ultraprocessing isn't what's making the foot hyperpalatable or low-satiety (the macronutrient mix and sweetening is).

The previous comment was pointing out that there's an agreed-on definition of what "ultra-processing" means. There is. But there is no such agreement on mechanistic effects of ultra-processing.