This thread is quite strange.
OP, is it you who wants your dd to look as though she can afford to wear branded clothes and wear expensive make-up?
She clearly wants to take a cut in income - which she is responsible for earning, anyway - so that she can concentrate on study.
But you are asking if she's unreasonable?
It's weird. Usually, it would be the parent trying to explain to the child that they don't need all that stuff and asking the child to cut down on working hours and concentrate on studying.
And, if she's now responsible for earning her money, and you're all OK with that, you've effectively made her responsible for her decision about working, anyway. So, to cut a long story short, you long ago decided that it's not your business, anyway.
I find it pretty strange. And I do wonder what else is going on in your relationship with your dd. I suspect it's more complicated than it seems from your initial OP.
I also wonder why you became so upset when people started saying that she didn't need stuff, and that the basics (food, travel, course costs) were possibly your remit. You sound extremely sensitive about the giving up of branded items. Do you have a background of being poor? Are you over-sensitive to your child appearing to be less well-off? Dies that matter to you?
(You do not have to answer any of these questions - they are your business, not mine. I just put them out there for you to think about.)
Because, otherwise, the answer is a completely straightforward: "Good decision. She is not at all unreasonable. She sounds mature."