diff --git a/libtaskmanager/xwindowtasksmodel.cpp b/libtaskmanager/xwindowtasksmodel.cpp
--- a/libtaskmanager/xwindowtasksmodel.cpp
+++ b/libtaskmanager/xwindowtasksmodel.cpp
@@ -535,17 +535,25 @@
 {
     const AppData &data = appData(window);
 
+    QUrl url = data.url;
+
     if (!encodeFallbackIcon || !data.icon.name().isEmpty()) {
-        return data.url;
+        return url;
     }
 
-    QUrl url = data.url;
-
     // Forego adding the window icon pixmap if the URL is otherwise empty.
     if (!url.isValid()) {
         return QUrl();
     }
 
+    // If we have a proper service for an application, there's most likely an icon on disk
+    // that goes with it, no need to serialize it.
+    // QIcon::name() used above only works for icons created from an icon theme, not when
+    // created using from an absolute path, as can be the case with e.g. containerized apps.
+    if (url.scheme() == QLatin1String("applications")) {
+        return url;
+    }
+
     const QPixmap pixmap = KWindowSystem::icon(window, KIconLoader::SizeLarge, KIconLoader::SizeLarge, false);
     if (pixmap.isNull()) {
         return data.url;