Ok. You could login using your external USB keyboard to login into the icewm Xsession, but I guess there the internal keyboard won't work either unless you're using gdm running on Wayland and KDE session was also a Wayland session and the issue only occurs on Wayland, but not on X. What you could try is uninstalling xf86-input-libinput package. If this fixes this, it's the same issue as boo#1175599