@lovelei As Ohm888 stated, you might’ve been a borderline candidate and they need those winter grades to make a decision. Yes you are right, not everyone got that email. Although idk what high school students getting early acceptances has do to with anything, as they don’t do early acceptances for us.
You might’ve been just a random audit tho. Also, if you were taking some important classes for the winter, like a major prereq or an English class, they might want to see those grades to make a more informed decision on your admission. Your gpa is pretty good tho for UCSC I’m sure you’re not gonna have issues getting into there.