When you open an Amazon seller account and found that it shows 'at risk' status, it means your Amazon account at risk of getting your Amazon account suspended. This status on Amazon depends upon the complaints you have received in the past 90 days.
If you have complaints against your account in several categories, then that can lead to Amazon account at risk. It can be an early alarm for you to fix all these complaints against your seller account to prevent the Amazon account suspended. These complaints may include "not as advertised' complaints, "Fake" or "counterfeit" products, "not as expected" items, late dispatch complaints by buyers, intellectual property complaints, and high order defect rate, etc.
The new “At Risk” status alert indicates how many complaints you've received for the past 90 days and for which items in your inventory. Amazon also broke things down by complaint category for you, as they have in the past.