When hiding a window by setting `visible = false` or deleting it with a loader, the wayland connection dies with the message "Tried to add event to destroyed queue" with a related warning slightly before.

This is reproducible by running the following qml snippet:

$ QSG_RHI_BACKEND=vulkan WAYLAND_DEBUG=1 qml test.qml

import QtQuick
import QtQuick.Window
Window {
    id: window
    visible: true
    Timer {
        running: true
        interval: 500
        onTriggered: window.visible = false
    }
}

The full log from the snippet above is attached.
 

Note that this does not just apply to xdg_shell windows, but custom shell integrations as well, though interestingly does not appear to apply to xdg_popups.