Please be precise with details, as the Start Here Guide tells you
There is no Kubuntu 26.x release
Zenity is an open source tool which has a very different purpose; ie. the Wikipedia page can be found here with that definition fitting what my own Ubuntu system describes it as (which is not an installer)
guiverc@d7050-next:/de2900/lubuntu_64$ apt info zenity
...
Original-Maintainer: Debian GNOME
...
Description: Display graphical dialog boxes from shell scripts
Zenity allows you to display GTK+ dialogs from shell scripts; it is a
rewrite of the `gdialog' command from GNOME 1.
Your installer may in fact use Zenity; but as its a tool only to show data on screen (in a formatted way from terminal), providing link to what you mean (if it’s different) should be provided.