An ad that one of my advisors shared contains a sentence that is against law and working ethic, and I am surprised to see an associate professor request from a postdoc to stay more than 10 h per day. I need advice how to report this behavior and what legal consequences this professor can face. Is this a suitable place?
In general, parts of this question (“I need advice how to report this behavior”) are on-topic. However, before asking, please consider:
Except for blatant cases, we cannot judge whether something is illegal and what consequences it has. Therefore it is usually better that you assume it as given that the sentence in question is illegal and only briefly describe its nature – instead of quoting the advertisement. If I understand your question correctly, it should suffice to say something along the lines of the following:
The advertisement requires the postdoc to work more than 10 h per day, which is clearly against the work laws of the respective jurisdiction.
Even if you anonymise all names and similar, the sentence in question may be specific enough to find the actual advertisement, connect it to your question, and identify you as the whistleblower.
Please specify what your goal and motivation are: Do you want this to cause high or minimum noise? Do you want to stay anonymous? Do you want the consequences to be high or low? Why?
I agree with Wrzlprmft's answer, but to expound on his last point: what goal will your question serve? If you suspect/know that some researcher somewhere is doing something wrong, contact that university's legal department, or graduate student ombudsman, or department chair, or any of the many people in that school who are there to ensure that stuff like this doesn't happen.
We can provide opinions and insights, but oftentimes you'll get a better answer by simply taking advantage of university resources.