citation key author vs. editor
The new Citation Key field automatically pulls from the author/editor field that is on "top," rather than from the "author" field. This is annoying for book sections, where the editor names generally appear first in the list of editors / authors (when pulling the info from websites with citations). To change the Citation Key, you have to click "move up" multiple times so that the authors appear on the top of the author/editor list, which is really annoying, especially since the order doesn't typically matter for a citation to be inserted into a document with the correct information/order.
That said, for Zotero's built-in bibtex export, we decided against "fixing" this because it would break existing citekeys, which is highly undesirable even though I agree that having this work correctly from the start would have been preferable. (The logic here is that a citekey is a machine-readable identifier before it is a human-readable one, so doing the former right is more important than the latter).