The Linux Mint project has at times forked various open-source projects to evolve them on their own such as the Cinnamon desktop starting out as forks of several GNOME 3 components. While their software forks and focus has mostly been at the desktop-level, they are going a bit further down the stack now to develop forks of several APT components that power package management on Debian/Ubuntu systems.
The text says “several”, but it mentions only four components (gdebi, apturl, aptdaemon and mintcommon-aptdaemon) merged into two (captain, aptkit). It doesn’t look like much, and typically the Mint project is responsible to not claim to maintain more than it can maintain¹.
In special, I remember gdebi being broken for quite a while², so this hints that Mint’s goal is to get properly maintained replacements.