According to the github page for Bazaar (which I may not be fully understanding correctly), it seems like Bazaar is designed for GNOME primarily, and then there is essentially a seperate thing, basically a kind of plugin or sort of like a patch, that is layered over top of the main Bazaar, which enables it to work with/in KDE.

Bazaar proper:

https://github.com/kolunmi/bazaar

Bazaar is fast and highly multi-threaded, guaranteeing a smooth experience in the user interface. You can queue as many downloads as you wish and run them while perusing Flathub's latest releases. This is due to the UI being completely decoupled from all backend operations.

It runs as a service, meaning state will be maintained even if you close all windows, and implements the gnome-shell search provider dbus interface. A krunner plugin is available for use on the KDE Plasma desktop.

The krunner plugin:

https://github.com/ublue-os/krunner-bazaar

A KRunner plugin for searching and installing Flatpak applications through the Bazaar store.

Sorry, I'm not a fequent KDE user, I may be misunderstanding something here.