https://bugs.kde.org/show_bug.cgi?id=372346#c3 says:

Wayland is a completely new graphics system. Nothing will run there unless the framework and/or application ports to that stack. For Qt, unless you ship the Wayland platform plugin, your application has no chance to run.

I have a hard time believing that given that Fedora already has switched to Wayland and apps apparently are still running there but if true, then linuxdeployqt better starts deploying the Wayland platform plugin whenever libQtXGui.so is being deployed.