diff --git a/deleted.h b/deleted.h
--- a/deleted.h
+++ b/deleted.h
@@ -172,6 +172,15 @@
         return m_transients;
     }
 
+    /**
+     * Returns whether the client was a popup.
+     *
+     * @returns @c true if the client was a popup, @c false otherwise.
+     **/
+    bool isPopupWindow() const override {
+        return m_wasPopupWindow;
+    }
+
 protected:
     virtual void debug(QDebug& stream) const;
 private Q_SLOTS:
@@ -223,6 +232,7 @@
     bool m_wasGroupTransient;
     ToplevelList m_transientFor;
     DeletedList m_transients;
+    bool m_wasPopupWindow;
 };
 
 inline void Deleted::refWindow()
diff --git a/deleted.cpp b/deleted.cpp
--- a/deleted.cpp
+++ b/deleted.cpp
@@ -52,6 +52,7 @@
     , m_wasX11Client(false)
     , m_wasWaylandClient(false)
     , m_wasGroupTransient(false)
+    , m_wasPopupWindow(false)
 {
 }
 
@@ -142,6 +143,7 @@
 
     m_wasWaylandClient = qobject_cast<ShellClient *>(c) != nullptr;
     m_wasX11Client = !m_wasWaylandClient;
+    m_wasPopupWindow = c->isPopupWindow();
 }
 
 void Deleted::unrefWindow()
diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -785,7 +785,6 @@
     bool managed = false;
     bool waylandClient;
     bool x11Client;
-    bool popupWindow;
 };
 
 EffectWindow::Private::Private(EffectWindow *q)
@@ -808,7 +807,6 @@
 
     d->waylandClient = parent->inherits("KWin::ShellClient");
     d->x11Client = !d->waylandClient;
-    d->popupWindow = parent->property("popupWindow").value<bool>();
 }
 
 EffectWindow::~EffectWindow()
@@ -858,6 +856,7 @@
 WINDOW_HELPER(bool, skipsCloseAnimation, "skipsCloseAnimation")
 WINDOW_HELPER(KWayland::Server::SurfaceInterface *, surface, "surface")
 WINDOW_HELPER(QVector<int>, desktops, "x11DesktopIds")
+WINDOW_HELPER(bool, isPopupWindow, "popupWindow")
 
 QString EffectWindow::windowClass() const
 {
@@ -1020,11 +1019,6 @@
     return d->x11Client;
 }
 
-bool EffectWindow::isPopupWindow() const
-{
-    return d->popupWindow;
-}
-
 //****************************************
 // EffectWindowGroup
 //****************************************
diff --git a/shell_client.cpp b/shell_client.cpp
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -1935,6 +1935,9 @@
 
 bool ShellClient::isPopupWindow() const
 {
+    if (Toplevel::isPopupWindow()) {
+        return true;
+    }
     if (m_shellSurface != nullptr) {
         return m_shellSurface->isPopup();
     }