zipdetails - Display details about the internal structure of Zip files. · GitHub

: In cybersecurity, files with unconventional naming may sometimes be associated with "Zombie ZIP" methods, where attackers malform headers to bypass antivirus detection .

If you have verified the file is safe, use reputable utilities to handle the archive:

: The "421" may denote a version number or build (e.g., version 4.2.1) for a specific software project, such as a plugin, mod, or custom script.