The "7zip" package is the official one. Linux support has been around before 22.00, but still relatively new. The old one is called "p7zip":

https://packages.ubuntu.com/jammy/p7zip

That one hasn't seen new releases since 2016.

The 7zz refers to the new binary name, which is different between the p7zip and 7zip packages.

dfsg in the package version is a note that it's been taken directly from Debian.