While version 16.61 was largely focused on and bug fixes rather than major new features, it belongs to the version 16 series which introduced:
Native support for newer functions like XLOOKUP , LET , and LAMBDA in later builds of this series. Microsoft Excel for Mac 16.61
Support for co-authoring and AutoSave for files stored on OneDrive or SharePoint. While version 16
For a complete history of builds and specific security updates, you can refer to the official Office for Mac update history on Microsoft Learn. Microsoft Excel for Mac 16.61