diff --git a/python/core/auto_generated/qgsgrouplayer.sip.in b/python/core/auto_generated/qgsgrouplayer.sip.in
index bb3b03100dd..03fbcd49235 100644
--- a/python/core/auto_generated/qgsgrouplayer.sip.in
+++ b/python/core/auto_generated/qgsgrouplayer.sip.in
@@ -108,6 +108,17 @@ Sets the current paint ``effect`` for the renderer.
 Ownership is transferred to the renderer.
 
 .. seealso:: :py:func:`paintEffect`
+%End
+
+    void prepareLayersForRemovalFromGroup();
+%Docstring
+Prepares all child layers in the group prior to removal from the group.
+
+This method should be called before removing a group layer from a project, to ensure
+that the existing child layers are in a state which is compatible with non-group
+layer children.
+
+.. versionadded:: 3.30
 %End
 
 };
diff --git a/src/core/layertree/qgslayertreegroup.cpp b/src/core/layertree/qgslayertreegroup.cpp
index 80ae191acab..b05d4d9eeb3 100644
--- a/src/core/layertree/qgslayertreegroup.cpp
+++ b/src/core/layertree/qgslayertreegroup.cpp
@@ -490,15 +490,7 @@ void QgsLayerTreeGroup::setGroupLayer( QgsGroupLayer *layer )
   {
     if ( !layer )
     {
-      // clearing the group layer -- ensure all child layers have consistent settings
-      const QList< QgsMapLayer * > children = groupLayer->childLayers();
-      for ( QgsMapLayer *child : children )
-      {
-        if ( QgsPainting::isClippingMode( QgsPainting::getBlendModeEnum( child->blendMode() ) ) )
-        {
-          child->setBlendMode( QPainter::CompositionMode_SourceOver );
-        }
-      }
+      groupLayer->prepareLayersForRemovalFromGroup();
     }
   }
   mGroupLayer.setLayer( layer );
diff --git a/src/core/qgsgrouplayer.cpp b/src/core/qgsgrouplayer.cpp
index 4bc8e18bb3a..d9acf3a065c 100644
--- a/src/core/qgsgrouplayer.cpp
+++ b/src/core/qgsgrouplayer.cpp
@@ -289,9 +289,15 @@ void QgsGroupLayer::setChildLayers( const QList< QgsMapLayer * > &layers )
   }
   for ( QgsMapLayer *layer : currentLayers )
   {
-    if ( !layers.contains( layer ) )
+    if ( layer && !layers.contains( layer ) )
     {
+      // layer removed from group
       disconnect( layer, &QgsMapLayer::repaintRequested, this, &QgsMapLayer::triggerRepaint );
+
+      if ( QgsPainting::isClippingMode( QgsPainting::getBlendModeEnum( layer->blendMode() ) ) )
+      {
+        layer->setBlendMode( QPainter::CompositionMode_SourceOver );
+      }
     }
   }
   mChildren = _qgis_listRawToRef( layers );
@@ -331,6 +337,17 @@ void QgsGroupLayer::setPaintEffect( QgsPaintEffect *effect )
   mPaintEffect.reset( effect );
 }
 
+void QgsGroupLayer::prepareLayersForRemovalFromGroup()
+{
+  for ( const QgsMapLayerRef &child : std::as_const( mChildren ) )
+  {
+    if ( child.get() && QgsPainting::isClippingMode( QgsPainting::getBlendModeEnum( child->blendMode() ) ) )
+    {
+      child->setBlendMode( QPainter::CompositionMode_SourceOver );
+    }
+  }
+}
+
 //
 // QgsGroupLayerDataProvider
 //
diff --git a/src/core/qgsgrouplayer.h b/src/core/qgsgrouplayer.h
index b1ff9ef734f..f3362bbbd0e 100644
--- a/src/core/qgsgrouplayer.h
+++ b/src/core/qgsgrouplayer.h
@@ -126,6 +126,17 @@ class CORE_EXPORT QgsGroupLayer : public QgsMapLayer
      */
     void setPaintEffect( QgsPaintEffect *effect SIP_TRANSFER );
 
+    /**
+     * Prepares all child layers in the group prior to removal from the group.
+     *
+     * This method should be called before removing a group layer from a project, to ensure
+     * that the existing child layers are in a state which is compatible with non-group
+     * layer children.
+     *
+     * \since QGIS 3.30
+     */
+    void prepareLayersForRemovalFromGroup();
+
   private:
 
     QgsGroupLayerDataProvider *mDataProvider = nullptr;