'Natural flavors' appears on tens of thousands of products, usually right where you'd want the most information and get the least.
What it legally means: flavor compounds derived from plant or animal sources — spices, fruit, vegetables, yeast, bark, roots [1]. The 'natural' part refers to the ORIGIN of the flavor molecules, not to simplicity. A single 'natural flavor' can be a formulation of dozens of compounds, built by the same flavor houses that make artificial flavors, and the recipe is a trade secret. Neither you nor rootd gets to see inside.
Is that dangerous? Usually not — flavor compounds are used in tiny amounts and reviewed for safety. The honest concern is different: opacity and purpose. Flavoring exists to make a product taste like something. If a strawberry yogurt needs 'natural flavors' to taste like strawberries, that tells you something about how much strawberry is involved.
There's also a practical edge case rootd cares about: allergies and strict diets. Flavor formulations can technically contain carriers and compounds a label doesn't itemize. For most people this is irrelevant; for the highly sensitive, it's why 'always verify with the manufacturer' exists.
How to read it like a pro: 'natural flavors' low on a list of real ingredients is seasoning. 'Natural flavors' near the top, propping up a product whose namesake ingredient is missing, is a costume. The term isn't a red flag — it's a flashlight pointed at the rest of the list.