Decline in food quality is ostensibly a decline in food security. But any sensible design would not use that as a threshold for defining food security.
Rather than appealing to some unnamed source’s cherry picked definition, you would do better to look at an actual study of food security and see how it was defined. Because a very small amount of common sense suggests to me it’s not what you’re saying.
> Low food security—Households reduced the quality, variety, and desirability of their diets, but the quantity of food intake and normal eating patterns were not substantially disrupted. [1]
In other words, by new definitions, if you ever reduce the quality, variety, or even desirability of your food throughout the year, you are considered food insecure.
EDIT: It looks like I'm not allowed to post in this thread anymore. I am quoting the USDA website. Nothing is cherry-picked. I've added a citation.
[1] https://www.ers.usda.gov/topics/food-nutrition-assistance/fo...