Here is a good, scientifically informed overview of one popular ultra processed food categorization system and why it excludes good foods and includes poor ones: https://www.eatrightpro.org/news-center/practice-trends/examining-the-nova-food-classification-system-and-healthfulness-of-ultra-processed-foods
The same kind of thing applies to the other popular systems for defining it. It's just not a good scientific category, we already know about all the components it's a mediocre shorthand for.