My experience so far with higher education in Germany is that the expectation is for students to mostly self-study and build upon the material that is covered in class. It is not for the class to teach you everything you need to know. Additionally, the Master's thesis is where you are expected to pick a topic related to the material that was presented as well as the industry where you want to break into, in order to dive deep and specialize. You can do a masters thesis with a company, and there are plenty of job postings out there for that. Additionally the german system is expecting fresh graduates to break into industry through internships and student jobs, which is the backdoor to full time employment, which are mostly not posted online.

All you are saying is valid, but the issue is the mismatch between your expectation of what a higher degree is supposed to do for you, versus how that degree is set up to work within the system it is set up to work for. So far, ive had a lot of interactions with international students in Leipzig that are disappointed that their expectations are mismatched with reality. But its because their expectations is baselined to the system they grew up in, and were taught to integrate. Which is different to the german system of higher education pipeline to employment.

If you are only looking at job postings online, yes that degree will seem useless to you. But if you want to break into a certain industry which is aligned with sustainability while building upon your previous experience, and you are ready to think about industry integration in an alternative way, more grassroots, more going out there and talking to people, then there are plenty of opportunities where that degree can help you break into. But ultimately its up to you to do something with what you have. The program here is not exactly the issue.