That sort of depends on the situation. Responsible disclosure is for if there is some relevant security hole that is an actual risk to businesses and people, while this here is just "haha look LLMs can now better pretend to write good text if you tell it to". That's not really responsible disclosurable. It's not even specific to one singular product.
This is sadly not easily generalizable, since a lot of people still use legacy operating systems with filesystems like NTFS, which as far as I know is not COW.
It's because of the old notion of "be generous in what you accept and strict in what you send". I think the error is something about adding more parent directories so that part of your zip file will be extracted above the selected directory. Not all implementations of zip support this "feature".
There are also all kinds of stupid ancient features in tar and zip from a time when hard drives were measured in megabytes or less. The latest episode of the open source security podcast talks about it.
That's like saying Feuetzeug is not a real German word because it's just the words Feuer and Zeug and it's kinda like saying "fire thing" in Britain