Since you’re on Aurora (KDE), can you try running this via the terminal: flatpak run org.chromium.Chromium --enable-wayland-ime --gtk-version=4 and see if it works then? (If --gtk-version=4 doesn’t work, maybe try --gtk4). If it works, you can add them to the Chromium config file, like so:
~/.var/app/org.chromium.Chromium/config
> cat chromium-flags.conf
## enable wayland & hardware acceleration
--ozone-platform-hint=auto
--enable-features=VaapiVideoDecodeLinuxGL,WebRTCPipeWireCapturer
## input method
--enable-wayland-ime
--gtk-version=4
If it doesn’t work, you might want to try Fcitx5 instead of ibus. According to this Fcitx5 input switching should work fine with Chromium (and most likely Electron apps) if you’re using KDE. (It doesn’t work yet in GNOME, unfortunately).