Found this writing a unit test. If a client calls requestMinimize before the first buffer then it won't get shown, which means wayland server never gets the shellClientAdded signal. This is problematic as it means we won't expose it to plasma, so a user can't unminimise it. I've added a unit test with a QEXPECT_FAIL for now
Do you know which test it was?
TestXdgShellClient::testXdgInitiallyMinimized()