hours being cut to zero?

i’m a “new” tm within my first 90 days and considered seasonal. this is my 3rd time working at target over the course of 6 years, and things have always ended on good terms.

my store is in a college town with a lot of students as tms. this summer i worked 40 hrs a week, getting that each week, when all i heard from everyone was that it was harder to get hours over the summer than it was during the school year. school has just started, im a student, and i cut down my desired hours to 20.

since i have changed my availability and desired hours, i went from them starting to schedule me 4 hours a week to zero. is this even legal? someone told me target is required to give you a certain percentage of your required hours, but im here for advice.