No, that's just the Mac version of the icon, which we consider the canonical version. The Windows/Linux one has less-rounded corners to fit in better with platform conventions (such as they are).
Oh, good to know, because I thought that the icon with the more rounded corners is the most recent one and is valid for all platforms, as it was shown in the official release notes:
https://s3.amazonaws.com/zotero.org/images/forums/u6/ms5dxh2l8zhbwiyw1wa7.png
https://s3.amazonaws.com/zotero.org/images/forums/u5698380/iqp1nzxi07fcmgz8v25e.png
The old icon was totally different:
https://s3.amazonaws.com/zotero.org/images/forums/u6/pfiu2ksl619o2w9b3jw1.png
https://s3.amazonaws.com/zotero.org/images/forums/u5698380/fhrlurzs3ilnof404yyw.png
Anyway, you are doing an awesome work, huge thanks!