Comment # 1 on bug 1222993 from Muhammad Refa Utama Putra

Agree. KDE Plasma 6 already have qt6-wayland installed, but the keyboard needs
libqt5-qtwayland. Below is the details on how I fix the problem

When running maliit-keyboard in Konsole, I got this message: qt.qpa.plugin:
Could not find the Qt platform plugin "wayland" in ""

qt6-wayland that provides /usr/lib64/qt6/plugins/platforms/libqwayland*.so has
been installed.
Problem solved by installing libqt5-qtwayland that provides
/usr/lib64/qt5/plugins/platforms/libqwayland*.so

So libqt5-qtwayland should be added as a dependency for maliit-keyboard