SUMMARY
Ibus Wayland breaks Firefox search bar autocomplete. I use Zen Browser but have also tested on Firefox and it doesn't work either.

STEPS TO REPRODUCE
1. Launch System Settings
2. Under the Input & Output, click Keyboard, then click Virtual Keyboard
3. Set to Ibus Wayland
4. Add `unset QT_IM_MODULE` and `unset GTK_IM_MODULE` to the end of `~/.bashrc`
5. Restart (or Log Out then Log In)
6. You should NOT see any Ibus notification (see [1] below).
7. Open Firefox / Zen Browser
8. Try searching for something by typing into the search bar
9. Observed result 1
10. Open konsole, run `ibus exit` then `ibus start`
11. A Ibus notification (see [1] below) should appear
12. Observed result 2.

OBSERVED RESULT
1. Autocomplete doesn't show up and therefore pressing right arrow key doesn't autocomplete
2. Autocomplete show up and pressing right arrow key autocomplete

EXPECTED RESULT
Autocomplete show up and works.

SOFTWARE/OS VERSIONS
KDE Neon 6.2 (based on Ubuntu 24.04, I recently upgraded)
KDE Plasma Version: 6.2.1
KDE Frameworks Version: 6.7.0
Qt Version: 6.7.2

ADDITIONAL INFORMATION
Kernel Version: 6.8.0-47-generic (64-bit)
Graphics Platform: Wayland

[1] IBus should be called from the desktop session in Wayland. For KDE, you can launch 'systemsettings5' utility and go to "Input Devices" -> "Virtual Keyboard" section and select "IBus Wayland" icon and click "Apply" button to configure IBus in Wayland. For other desktop sessions, you can copy the 'Exec=' line in org.freedesktop.IBus.Panel.Wayland.Gtk3.desktop file to a configuration file of the session. Please refer each document about the "Wayland input method" configuration. Before you configure the "Wayland input method", you should make sure that QT_IM_MODULE and GTK_IM_MODULE environment variables are unset in the desktop session.