In my experience, the Mozilla apt repo would still have dependencies on system libraries that can only be installed by updating the operating system to another LTS. Like, the Mozilla Firefox package depends on libssl, which depends on another package and that other package can only be updated by updating the operating system, which typically drastically changes the look and feel of system menus and things that are not easily gleaned by looking at a screenshot of an empty desktop. Maybe this isn't true of KDE and the interface remains stable across to update cycles. Thank you for the suggestion.