Contra this article, I'd highly recommend the book it mentions: Ultra-Processed People by Chris van Tulleken. It collates a lot of good studies and evidence that highly processed food is less healthy in and of itself, even if macro- and micronutrient composition is identical. It also covers a lot of the misbehavior and lobbying by food companies, marketing to create addictive behavior, as well as the engineering going on to create hyperpalatable foods.

My diet's generally clean, but the book was a great reminder/jumpstart with clear guidance (eat less processed food) that's not preachy or prescriptive.