The answers you have so far are predictable here, where *anyone* spending that much on Starbucks is too much. (and, I agree) But, you have a bigger issue, that you hint at. As always, first some more questions:
1) What is your income? Is €500 a lot to you? Is €10?
2) What was your agreement when she came to Germany? Did you agree on a specific amount of help? Have you come to the current arrangement only afterward? How specific is it?
For a start, she should have a budget she needs to live within. Whether or not it is the current budget depends on both of the above questions. In essence, what was she expecting, and did she have good reason to expect it? And, will it seem "fair" to her? That is, if she can't have Starbucks, but you do, will she be upset? Or. would she see the observations you have about her lifestyle reflected in your own lifestyle?
If you have not yet talked about money in detail, this may be a difficult time. It sounds like she is used to at least some luxury: whether it was by her own career in Brazil, or parental support. It is important to see if she *wants* to act more maturely--she did, after all, move to a different continent. But if it was simply for thrill / adventure, it might be a bad sign. If it was to become established with you in Germany, then you should be able to get through this discussion.
On the other side, when might she be able to work? Is there a process to get a work permit, and has she started it? Or, is she allowed to do crafts / blogging / tutoring or some other personal kind of business?