It's not, but if it's not your strong suit it doesn't make you a bad student to struggle in the class. Could Zoey have managed her time better studying for the class after dropping design lab? Sure. But a C- in a class that isn't her strong suit isn't proof that she's a bad student or not committed to her education.
Actually it is a mature decision when the class is primarily based of creating projects. And college students are allowed to change their minds about their classes and majors if they aren't feeling fulfilled. That's the whole point of college.
Had Zoey had the opportunity to explain her decision to her parents, they likely would've understood. But because Grownish is drenched in misogyny, Zoey must be punished for having something resembling a consistent character arc.
Who said that?
No, it doesn't. There are plenty of kids who study harder & manage time much better than Zoey, who struggle as bad or worse in college. That doesn't make them bad students, just like it doesn't for Zoey. Prior to dropping design lab, she was doing really well academic-wise, so it's not as if she was slacking the whole season. Sure, Zoey was partying a lot, but it wasn't partying that initially caused her to struggle academically.