Backport from 6.6 branch which failed to make it in 6.6.2.

https://bugreports.qt.io/browse/QTBUG-95817
https://codereview.qt-project.org/c/qt/qtwayland/+/536732
https://github.com/qt/qtwayland/commit/e4156bad6398dcbe8740041148d95ee9ed437d8b
From: David Redondo <qt@david-redondo.de>
Date: Wed, 31 Jan 2024 09:01:48 +0100
Subject: [PATCH] client: Disable threaded GL on desktop NVIDIA

Otherwise QtQuick windows freeze when resized.
In order to still use threaded rendering on
embedded platforms where resizing is not required
we check if XDG_CURRENT_DESKTOP which should be
set by  desktop environments.
--- a/src/hardwareintegration/client/wayland-egl/qwaylandeglclientbufferintegration.cpp
+++ b/src/hardwareintegration/client/wayland-egl/qwaylandeglclientbufferintegration.cpp
@@ -92,6 +92,13 @@ void QWaylandEglClientBufferIntegration::initialize(QWaylandDisplay *display)
             break;
         }
     }
+
+    // On desktop NVIDIA resizing QtQuick freezes them when using threaded rendering QTBUG-95817
+    // In order to support threaded rendering on embedded platforms where resizing is not needed
+    // we check if XDG_CURRENT_DESKTOP is set which desktop environments should set
+    if (qstrcmp(vendor, "NVIDIA") == 0 && qEnvironmentVariableIsSet("XDG_CURRENT_DESKTOP")) {
+        m_supportsThreading = false;
+    }
 }
 
 bool QWaylandEglClientBufferIntegration::isValid() const