diff --git a/src/core/mesh/qgsmeshdatasetgroupstore.cpp b/src/core/mesh/qgsmeshdatasetgroupstore.cpp
index 810ab6286b8b..4112f2b31b88 100644
--- a/src/core/mesh/qgsmeshdatasetgroupstore.cpp
+++ b/src/core/mesh/qgsmeshdatasetgroupstore.cpp
@@ -343,6 +343,16 @@ void QgsMeshDatasetGroupStore::readXml( const QDomElement &storeElem, const QgsR
     setDatasetGroupTreeItem( new QgsMeshDatasetGroupTreeItem( rootTreeItemElem, context ) );
 }
 
+int QgsMeshDatasetGroupStore::globalDatasetGroupIndexInSource( QgsMeshDatasetSourceInterface *source, int nativeGroupIndex ) const
+{
+  for ( QMap<int, DatasetGroup>::const_iterator it = mRegistery.cbegin(); it != mRegistery.cend(); ++it )
+  {
+    if ( it.value().first == source && it.value().second == nativeGroupIndex )
+      return it.key();
+  }
+
+  return -1;
+}
 
 bool QgsMeshDatasetGroupStore::saveDatasetGroup( QString filePath, int groupIndex, QString driver )
 {
diff --git a/src/core/mesh/qgsmeshdatasetgroupstore.h b/src/core/mesh/qgsmeshdatasetgroupstore.h
index 4861f53a89d0..0335765260d7 100644
--- a/src/core/mesh/qgsmeshdatasetgroupstore.h
+++ b/src/core/mesh/qgsmeshdatasetgroupstore.h
@@ -210,6 +210,14 @@ class QgsMeshDatasetGroupStore: public QObject
     //! Reads the store's information from a DOM document
     void readXml( const QDomElement &storeElem, const QgsReadWriteContext &context );
 
+    /**
+     * Returns the global dataset group index of the dataset group with native index \a globalGroupIndex in the \a source
+     * Returns -1 if the group or the source is not registered
+     *
+     * Since QGIS 3.22
+     */
+    int globalDatasetGroupIndexInSource( QgsMeshDatasetSourceInterface *source, int nativeGroupIndex ) const;
+
   signals:
     //! Emitted after dataset groups are added
     void datasetGroupsAdded( QList<int> indexes );
diff --git a/src/core/mesh/qgsmeshlayer.cpp b/src/core/mesh/qgsmeshlayer.cpp
index 57ce111321a7..33dcea473242 100644
--- a/src/core/mesh/qgsmeshlayer.cpp
+++ b/src/core/mesh/qgsmeshlayer.cpp
@@ -49,8 +49,7 @@ QgsMeshLayer::QgsMeshLayer( const QString &meshLayerPath,
                             const QString &providerKey,
                             const QgsMeshLayer::LayerOptions &options )
   : QgsMapLayer( QgsMapLayerType::MeshLayer, baseName, meshLayerPath ),
-    mDatasetGroupStore( new QgsMeshDatasetGroupStore( this ) ),
-    mTemporalProperties( new QgsMeshLayerTemporalProperties( this ) )
+    mDatasetGroupStore( new QgsMeshDatasetGroupStore( this ) )
 
 {
   mShouldValidateCrs = !options.skipCrsValidation;
@@ -207,11 +206,13 @@ bool QgsMeshLayer::supportsEditing() const
 
 QString QgsMeshLayer::loadDefaultStyle( bool &resultFlag )
 {
-  if ( mDataProvider )
-  {
-    for ( int i = 0; i < mDataProvider->datasetGroupCount(); ++i )
-      assignDefaultStyleToDatasetGroup( i );
+  const QList<int> groupsList = datasetGroupsIndexes();
+
+  for ( const int index : groupsList )
+    assignDefaultStyleToDatasetGroup( index );
 
+  if ( !groupsList.isEmpty() )
+  {
     emit rendererChanged();
     emitStyleChanged();
   }
@@ -1156,17 +1157,9 @@ void QgsMeshLayer::setDataSourcePrivate( const QString &dataSource, const QStrin
   mLayerName = baseName;
   setProviderType( provider );
 
-  // if we’re given a provider type, try to create and bind one to this layer
-  bool ok = false;
   if ( !mDataSource.isEmpty() && !provider.isEmpty() )
-  {
-    ok = setDataProvider( provider, options, flags );
-  }
+    setDataProvider( provider, options, flags );
 
-  if ( ok )
-  {
-    mTemporalProperties->setDefaultsFromDataProviderTemporalCapabilities( mDataProvider->temporalCapabilities() );
-  }
 }
 
 QgsPointXY QgsMeshLayer::snapOnElement( QgsMesh::ElementType elementType, const QgsPointXY &point, double searchRadius )
@@ -1504,6 +1497,8 @@ bool QgsMeshLayer::readXml( const QDomNode &layer_node, QgsReadWriteContext &con
   else
     mDatasetGroupStore->readXml( elemDatasetGroupsStore, context );
 
+  mTemporalProperties = new QgsMeshLayerTemporalProperties( this );
+
   setDataProvider( mProviderKey, providerOptions, flags );
 
   QString errorMsg;
@@ -1711,12 +1706,15 @@ bool QgsMeshLayer::setDataProvider( QString const &provider, const QgsDataProvid
     return false;
   }
 
+  if ( !mTemporalProperties )
+  {
+    mTemporalProperties = new QgsMeshLayerTemporalProperties( this );
+    mTemporalProperties->setDefaultsFromDataProviderTemporalCapabilities( dataProvider()->temporalCapabilities() );
+  }
+
   mDataProvider->setTemporalUnit( mTemporalUnit );
 
-  // temporarily disconnect from datasetGroupsAdded -- we don't want to reset the style for reconnected dataset groups
-  disconnect( mDatasetGroupStore.get(), &QgsMeshDatasetGroupStore::datasetGroupsAdded, this, &QgsMeshLayer::onDatasetGroupsAdded );
   mDatasetGroupStore->setPersistentProvider( mDataProvider, mExtraDatasetUri );
-  connect( mDatasetGroupStore.get(), &QgsMeshDatasetGroupStore::datasetGroupsAdded, this, &QgsMeshLayer::onDatasetGroupsAdded );
 
   setCrs( mDataProvider->crs() );
 
@@ -1726,16 +1724,17 @@ bool QgsMeshLayer::setDataProvider( QString const &provider, const QgsDataProvid
     mDataSource = mDataSource + QStringLiteral( "&uid=%1" ).arg( QUuid::createUuid().toString() );
   }
 
-  if ( flags & QgsDataProvider::FlagLoadDefaultStyle )
+  // set default style if required by flags or if the dataset group does not has a style yet
+  for ( int i = 0; i < mDataProvider->datasetGroupCount(); ++i )
   {
-    for ( int i = 0; i < mDataProvider->datasetGroupCount(); ++i )
-      assignDefaultStyleToDatasetGroup( i );
-
-    emit rendererChanged();
-    emitStyleChanged();
+    int globalIndex = mDatasetGroupStore->globalDatasetGroupIndexInSource( mDataProvider, i );
+    if ( globalIndex != -1 &&
+         ( !mRendererSettings.hasSettings( globalIndex ) || ( flags & QgsDataProvider::FlagLoadDefaultStyle ) ) )
+      assignDefaultStyleToDatasetGroup( globalIndex );
   }
 
-  temporalProperties()->setIsActive( mDatasetGroupStore->hasTemporalCapabilities() );
+  emit rendererChanged();
+  emitStyleChanged();
 
   connect( mDataProvider, &QgsMeshDataProvider::dataChanged, this, &QgsMeshLayer::dataChanged );
 
diff --git a/src/core/mesh/qgsmeshrenderersettings.cpp b/src/core/mesh/qgsmeshrenderersettings.cpp
index 0e56afcfbd82..baf46f799d42 100644
--- a/src/core/mesh/qgsmeshrenderersettings.cpp
+++ b/src/core/mesh/qgsmeshrenderersettings.cpp
@@ -740,3 +740,7 @@ void QgsMeshRendererVectorTracesSettings::setParticlesCount( int value )
   mParticlesCount = value;
 }
 
+bool QgsMeshRendererSettings::hasSettings( int datasetGroupIndex ) const
+{
+  return mRendererScalarSettings.contains( datasetGroupIndex ) || mRendererVectorSettings.contains( datasetGroupIndex );
+}
diff --git a/src/core/mesh/qgsmeshrenderersettings.h b/src/core/mesh/qgsmeshrenderersettings.h
index a90577fbdeb5..cc27c82e9a14 100644
--- a/src/core/mesh/qgsmeshrenderersettings.h
+++ b/src/core/mesh/qgsmeshrenderersettings.h
@@ -673,6 +673,13 @@ class CORE_EXPORT QgsMeshRendererSettings
      */
     void setActiveVectorDatasetGroup( int activeVectorDatasetGroup );
 
+    /**
+    * Returns whether the group with \a index has render settings (scalar or vector)
+    *
+    * \since QGIS 3.22
+    */
+    bool hasSettings( int datasetGroupIndex ) const;
+
   private:
     QgsMeshRendererMeshSettings mRendererNativeMeshSettings;
     QgsMeshRendererMeshSettings mRendererTriangularMeshSettings;