Thoughts
According to stackoverflow commenter blueberryfields The Unlicense isn't legally sound in Germany and you shouldn't use it!
All these arguments against public domain licenses seem to boil down to 'the license wasn't written by my lawyer' or 'it's impossible to public-domain code' or 'no one's ever proven in court that this license works.'
It's like, if you assume that no one else is acting in good faith and your goal is to avoid a lawsuit by whatever means necessary, then I don't know what you want from me. If you're going to assume that I'm going to try to sue you, and that the judge and jury are going to misinterpret anything I say now to hurt you in the future, then I don't know what I can say to convince you otherwise.
Like literally, The Unlicense is like 'you can use this code for any purpose' and people are like, 'I don't trust that, stackoverflow commenter blueberryfields said that's not a legal disclaimer under German copyright law.'
I'll update this post with the username of the actual stackoverflow user later, it wasn't blueberry but it was something like that. Edit (9:43): It was "blueberryfields"