Isn’t flood insurance not supposed to go up by more than 18% per year?

I see from past thread that many ppl's flood insurance premiums increased by more than 18%. From FEMA's own website though, it says

Limiting Annual Premium Increases Existing statutory limits on rate increases require that most rates not increase more than 18% per year.

I'm not sure what qualifies you for this restriction, but from a Forbes article, it says

Federal law states that FEMA can only raise rates by 5% to 18% a year. But that means that premiums could climb by more than 60% in three years. And it only applies to those who already have flood insurance, or who are buying a home with an existing flood insurance policy.

So what gives? Does anyone know how they determine if your rate can increase by more than 18% a year or not? Every article I read just says most policies won't increase by more than 18%, but don't specify further