diff --git a/src/gui/kernel/qplatformwindow.h b/src/gui/kernel/qplatformwindow.h
index 517dd1ea42..b6e96a457e 100644
--- a/src/gui/kernel/qplatformwindow.h
+++ b/src/gui/kernel/qplatformwindow.h
@@ -32,7 +32,6 @@ class QScreen;
 class QWindow;
 class QIcon;
 class QRegion;
-class QPlatformBackingStore;
 
 class Q_GUI_EXPORT QPlatformWindow : public QPlatformSurface
 {
@@ -118,8 +117,6 @@ public:
     virtual void requestUpdate();
     bool hasPendingUpdateRequest() const;
     virtual void deliverUpdateRequest();
-#define QT_PLATFORM_WINDOW_HAS_VIRTUAL_SET_BACKING_STORE // remove when all modules have migrated
-    virtual void setBackingStore(QPlatformBackingStore *) {}
 
     // Window property accessors. Platform plugins should use these
     // instead of accessing QWindow directly.
diff --git a/src/platformsupport/fbconvenience/qfbscreen.cpp b/src/platformsupport/fbconvenience/qfbscreen.cpp
index a5d87fec04..e804488005 100644
--- a/src/platformsupport/fbconvenience/qfbscreen.cpp
+++ b/src/platformsupport/fbconvenience/qfbscreen.cpp
@@ -47,7 +47,6 @@ bool QFbScreen::event(QEvent *event)
 
 void QFbScreen::addWindow(QFbWindow *window)
 {
-    Q_ASSERT(window->backingStore());
     mWindowStack.prepend(window);
     if (!mPendingBackingStores.isEmpty()) {
         //check if we have a backing store for this window
diff --git a/src/platformsupport/fbconvenience/qfbwindow.cpp b/src/platformsupport/fbconvenience/qfbwindow.cpp
index 8df50a14da..54716cc497 100644
--- a/src/platformsupport/fbconvenience/qfbwindow.cpp
+++ b/src/platformsupport/fbconvenience/qfbwindow.cpp
@@ -3,11 +3,9 @@
 
 #include "qfbwindow_p.h"
 #include "qfbscreen_p.h"
-#include "qfbbackingstore_p.h"
 
 #include <QtGui/QScreen>
 #include <qpa/qwindowsysteminterface.h>
-#include <qpa/qplatformbackingstore.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -113,11 +111,5 @@ void QFbWindow::repaint(const QRegion &region)
     for (auto rect : region)
         platformScreen()->setDirty(rect.translated(topLeft));
 }
-void QFbWindow::setBackingStore(QPlatformBackingStore *store)
-{
-    Q_ASSERT(store);
-    Q_ASSERT_X(dynamic_cast<QFbBackingStore *>(store), __FUNCTION__,
-               "Argument is not a QFbBackingStore.");
-    mBackingStore = static_cast<QFbBackingStore *>(store);
-}
+
 QT_END_NAMESPACE
diff --git a/src/platformsupport/fbconvenience/qfbwindow_p.h b/src/platformsupport/fbconvenience/qfbwindow_p.h
index 8848e9dcf8..8367a10bce 100644
--- a/src/platformsupport/fbconvenience/qfbwindow_p.h
+++ b/src/platformsupport/fbconvenience/qfbwindow_p.h
@@ -41,7 +41,7 @@ public:
 
     WId winId() const override { return mWindowId; }
 
-    void setBackingStore(QPlatformBackingStore *store) override;
+    void setBackingStore(QFbBackingStore *store) { mBackingStore = store; }
     QFbBackingStore *backingStore() const { return mBackingStore; }
 
     QFbScreen *platformScreen() const;
diff --git a/src/plugins/platforms/android/qandroidplatformbackingstore.cpp b/src/plugins/platforms/android/qandroidplatformbackingstore.cpp
index 33c422bb1e..09cc9ce8c6 100644
--- a/src/plugins/platforms/android/qandroidplatformbackingstore.cpp
+++ b/src/plugins/platforms/android/qandroidplatformbackingstore.cpp
@@ -25,10 +25,11 @@ void QAndroidPlatformBackingStore::flush(QWindow *window, const QRegion &region,
 {
     Q_UNUSED(offset);
 
-    if (!m_backingStoreSet)
+    auto *platformWindow = static_cast<QAndroidPlatformWindow *>(window->handle());
+    if (!platformWindow->backingStore())
         setBackingStore(window);
 
-    (static_cast<QAndroidPlatformWindow *>(window->handle()))->repaint(region);
+    platformWindow->repaint(region);
 }
 
 void QAndroidPlatformBackingStore::resize(const QSize &size, const QRegion &staticContents)
@@ -42,7 +43,6 @@ void QAndroidPlatformBackingStore::resize(const QSize &size, const QRegion &stat
 void QAndroidPlatformBackingStore::setBackingStore(QWindow *window)
 {
     (static_cast<QAndroidPlatformWindow *>(window->handle()))->setBackingStore(this);
-    m_backingStoreSet = true;
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/android/qandroidplatformbackingstore.h b/src/plugins/platforms/android/qandroidplatformbackingstore.h
index 810305ac45..b64a9f27bb 100644
--- a/src/plugins/platforms/android/qandroidplatformbackingstore.h
+++ b/src/plugins/platforms/android/qandroidplatformbackingstore.h
@@ -21,7 +21,6 @@ public:
     void setBackingStore(QWindow *window);
 protected:
     QImage m_image;
-    bool m_backingStoreSet = false;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/android/qandroidplatformscreen.cpp b/src/plugins/platforms/android/qandroidplatformscreen.cpp
index 2f33816824..54c7a34efe 100644
--- a/src/plugins/platforms/android/qandroidplatformscreen.cpp
+++ b/src/plugins/platforms/android/qandroidplatformscreen.cpp
@@ -43,7 +43,7 @@ public:
     }
 
 private:
-    QElapsedTimer m_timer;
+    QTime m_timer;
     QString m_msg;
 };
 
diff --git a/src/plugins/platforms/android/qandroidplatformwindow.cpp b/src/plugins/platforms/android/qandroidplatformwindow.cpp
index 1bc4a04b98..b1eba17d04 100644
--- a/src/plugins/platforms/android/qandroidplatformwindow.cpp
+++ b/src/plugins/platforms/android/qandroidplatformwindow.cpp
@@ -5,9 +5,9 @@
 #include "qandroidplatformwindow.h"
 #include "qandroidplatformopenglcontext.h"
 #include "qandroidplatformscreen.h"
-#include "qandroidplatformbackingstore.h"
+
 #include "androidjnimain.h"
-#include "qpa/qplatformbackingstore.h"
+
 #include <qguiapplication.h>
 #include <qpa/qwindowsysteminterface.h>
 #include <private/qhighdpiscaling_p.h>
@@ -169,12 +169,4 @@ void QAndroidPlatformWindow::applicationStateChanged(Qt::ApplicationState)
     QWindowSystemInterface::flushWindowSystemEvents();
 }
 
-void QAndroidPlatformWindow::setBackingStore(QPlatformBackingStore *store)
-{
-    Q_ASSERT(store);
-    Q_ASSERT_X(dynamic_cast<QAndroidPlatformBackingStore *>(store), __FUNCTION__,
-               "Argument is not a QAndroidPlatformBackingStore.");
-    m_backingStore = static_cast<QAndroidPlatformBackingStore *>(store);
-}
-
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/android/qandroidplatformwindow.h b/src/plugins/platforms/android/qandroidplatformwindow.h
index ee2771ee11..6fccc2e7fe 100644
--- a/src/plugins/platforms/android/qandroidplatformwindow.h
+++ b/src/plugins/platforms/android/qandroidplatformwindow.h
@@ -50,7 +50,7 @@ public:
 
     virtual void applicationStateChanged(Qt::ApplicationState);
 
-    void setBackingStore(QPlatformBackingStore *store) override;
+    void setBackingStore(QAndroidPlatformBackingStore *store) { m_backingStore = store; }
     QAndroidPlatformBackingStore *backingStore() const { return m_backingStore; }
 
     virtual void repaint(const QRegion &) { }
diff --git a/src/plugins/platforms/eglfs/api/qeglfswindow.cpp b/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
index 6210ef16a8..1a31f97d7b 100644
--- a/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
@@ -108,12 +108,8 @@ void QEglFSWindow::create()
 #endif
 }
 
-void QEglFSWindow::setBackingStore(QPlatformBackingStore *store)
+void QEglFSWindow::setBackingStore(QOpenGLCompositorBackingStore *backingStore)
 {
-    Q_ASSERT(store);
-    Q_ASSERT_X(dynamic_cast<QOpenGLCompositorBackingStore *>(store), __FUNCTION__,
-               "Argument is not a QOpenGLCompositorBackingStore.");
-    auto *backingStore = static_cast<QOpenGLCompositorBackingStore *>(store);
 #ifndef QT_NO_OPENGL
     if (!m_rasterCompositingContext) {
         m_rasterCompositingContext = new QOpenGLContext;
diff --git a/src/plugins/platforms/eglfs/api/qeglfswindow_p.h b/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
index d8e0a4a735..d111042040 100644
--- a/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
+++ b/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
@@ -71,7 +71,7 @@ public:
 
 #ifndef QT_NO_OPENGL
     QOpenGLCompositorBackingStore *backingStore() { return m_backingStore; }
-    void setBackingStore(QPlatformBackingStore *backingStore) override;
+    void setBackingStore(QOpenGLCompositorBackingStore *backingStore);
     QWindow *sourceWindow() const override;
     const QPlatformTextureList *textures() const override;
     void endCompositing() override;
diff --git a/src/plugins/platforms/wasm/qwasmwindow.cpp b/src/plugins/platforms/wasm/qwasmwindow.cpp
index 7a5cc19d13..21800e3b0b 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.cpp
+++ b/src/plugins/platforms/wasm/qwasmwindow.cpp
@@ -236,14 +236,6 @@ QWasmScreen *QWasmWindow::platformScreen() const
     return static_cast<QWasmScreen *>(window()->screen()->handle());
 }
 
-void QWasmWindow::setBackingStore(QPlatformBackingStore *store)
-{
-    Q_ASSERT(store);
-    Q_ASSERT_X(dynamic_cast<QWasmBackingStore *>(store), __FUNCTION__,
-               "Argument is not a QWasmBackingStore.");
-    m_backingStore = static_cast<QWasmBackingStore *>(store);
-}
-
 void QWasmWindow::paint()
 {
     if (!m_backingStore || !isVisible() || m_context2d.isUndefined())
diff --git a/src/plugins/platforms/wasm/qwasmwindow.h b/src/plugins/platforms/wasm/qwasmwindow.h
index 40f7a4df12..3e7f215b6f 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.h
+++ b/src/plugins/platforms/wasm/qwasmwindow.h
@@ -89,7 +89,7 @@ public:
     void setParent(const QPlatformWindow *window) final;
 
     QWasmScreen *platformScreen() const;
-    void setBackingStore(QPlatformBackingStore *store) override;
+    void setBackingStore(QWasmBackingStore *store) { m_backingStore = store; }
     QWasmBackingStore *backingStore() const { return m_backingStore; }
     QWindow *window() const { return m_window; }
 
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 64e55bd34b..b8ae2875a8 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -1332,11 +1332,6 @@ void QWidgetPrivate::create()
     QBackingStore *store = q->backingStore();
     usesRhiFlush = false;
 
-    // Re-use backing store, in case a new platform window was created and doesn't know about it.
-    // (e.g. QAndroidPlatformWindow)
-    if (store && q->windowHandle())
-        q->windowHandle()->handle()->setBackingStore(store->handle());
-
     if (!store) {
         if (q->windowType() != Qt::Desktop) {
             if (q->isWindow()) {