diff --git a/src/corelib/tools/qmap.h b/src/corelib/tools/qmap.h
index d09fa361a0..24d82fa22d 100644
--- a/src/corelib/tools/qmap.h
+++ b/src/corelib/tools/qmap.h
@@ -1316,33 +1316,24 @@ public:
         return iterator(d->m.insert(detachedPos, {key, value}));
     }
 
-    // CHANGE: provide insertMulti for compatibility
+#if QT_DEPRECATED_SINCE(6, 0)
+    QT_DEPRECATED_VERSION_X_6_0("Use insert() instead")
     iterator insertMulti(const Key &key, const T &value)
     {
         return insert(key, value);
     }
-
+    QT_DEPRECATED_VERSION_X_6_0("Use insert() instead")
     iterator insertMulti(const_iterator pos, const Key &key, const T &value)
     {
         return insert(pos, key, value);
     }
 
+    QT_DEPRECATED_VERSION_X_6_0("Use unite() instead")
     void insert(const QMultiMap<Key, T> &map)
     {
-        if (map.isEmpty())
-            return;
-
-        detach();
-
-        auto copy = map.d->m;
-#ifdef __cpp_lib_node_extract
-        copy.merge(std::move(d->m));
-#else
-        copy.insert(std::make_move_iterator(d->m.begin()),
-                    std::make_move_iterator(d->m.end()));
-#endif
-        d->m = std::move(copy);
+        unite(map);
     }
+#endif
 
     void insert(QMultiMap<Key, T> &&map)
     {
@@ -1402,7 +1393,19 @@ public:
 
     QMultiMap &unite(const QMultiMap &other)
     {
-        insert(other);
+        if (other.isEmpty())
+            return *this;
+
+        detach();
+
+        auto copy = other.d->m;
+#ifdef __cpp_lib_node_extract
+        copy.merge(std::move(d->m));
+#else
+        copy.insert(std::make_move_iterator(d->m.begin()),
+                    std::make_move_iterator(d->m.end()));
+#endif
+        d->m = std::move(copy);
         return *this;
     }
 };
diff --git a/src/corelib/tools/qmap.qdoc b/src/corelib/tools/qmap.qdoc
index 1857a05a13..b2ec6e15e4 100644
--- a/src/corelib/tools/qmap.qdoc
+++ b/src/corelib/tools/qmap.qdoc
@@ -781,6 +781,17 @@
     \sa QMultiMap::insert()
 */
 
+/*! \fn template <class Key, class T> void QMap<Key, T>::insert(QMap<Key, T> &&map)
+    \since 5.15
+
+    Moves all the items from \a map into this map.
+
+    If a key is common to both maps, its value will be replaced with
+    the value stored in \a map.
+
+    If \a map is shared, then the items will be copied instead.
+*/
+
 /*! \typedef QMap::Iterator
 
     Qt-style synonym for QMap<Key, T>::iterator.
@@ -943,7 +954,7 @@
 
     There is no direct way of changing an item's key through an
     iterator, although it can be done by calling QMap::erase()
-    followed by QMap::insert() or QMap::insertMulti().
+    followed by QMap::insert().
 
     \sa value()
 */
@@ -977,21 +988,21 @@
 */
 
 /*!
-    \fn template <class Key, class T> bool QMap<Key, T>::iterator::operator==(const iterator &other) const
-    \fn template <class Key, class T> bool QMap<Key, T>::iterator::operator==(const const_iterator &other) const
+    \fn template <class Key, class T> bool QMap<Key, T>::iterator::operator==(const iterator &lhs, const iterator &rhs)
+    \fn template <class Key, class T> bool QMap<Key, T>::const_iterator::operator==(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to the same item as this
-    iterator; otherwise returns \c false.
+    Returns \c true if \a lhs points to the same item as the \a rhs iterator;
+    otherwise returns \c false.
 
     \sa operator!=()
 */
 
 /*!
-    \fn template <class Key, class T> bool QMap<Key, T>::iterator::operator!=(const iterator &other) const
-    \fn template <class Key, class T> bool QMap<Key, T>::iterator::operator!=(const const_iterator &other) const
+    \fn template <class Key, class T> bool QMap<Key, T>::iterator::operator!=(const iterator &lhs, const iterator &rhs)
+    \fn template <class Key, class T> bool QMap<Key, T>::const_iterator::operator!=(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to a different item than this
-    iterator; otherwise returns \c false.
+    Returns \c true if \a lhs points to a different item than the \a rhs iterator;
+    otherwise returns \c false.
 
     \sa operator==()
 */
@@ -1150,22 +1161,6 @@
     \sa value()
 */
 
-/*! \fn template <class Key, class T> bool QMap<Key, T>::const_iterator::operator==(const const_iterator &other) const
-
-    Returns \c true if \a other points to the same item as this
-    iterator; otherwise returns \c false.
-
-    \sa operator!=()
-*/
-
-/*! \fn template <class Key, class T> bool QMap<Key, T>::const_iterator::operator!=(const const_iterator &other) const
-
-    Returns \c true if \a other points to a different item than this
-    iterator; otherwise returns \c false.
-
-    \sa operator==()
-*/
-
 /*! \fn template <class Key, class T> QMap<Key, T>::const_iterator &QMap<Key, T>::const_iterator::operator++()
 
     The prefix ++ operator (\c{++i}) advances the iterator to the
diff --git a/src/corelib/tools/qmultimap.qdoc b/src/corelib/tools/qmultimap.qdoc
index 01b2f17c73..8b3337e59b 100644
--- a/src/corelib/tools/qmultimap.qdoc
+++ b/src/corelib/tools/qmultimap.qdoc
@@ -259,9 +259,10 @@
     fast and never fails.
 */
 
-/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::operator==(const QMultiMap<Key, T> &other) const
+/*! \fn template<class Key, class T> bool operator==(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)
+    \relates QMultiMap
 
-    Returns \c true if \a other is equal to this multi map; otherwise returns
+    Returns \c true if \a lhs is equal to \a rhs; otherwise returns
     false.
 
     Two multi maps are considered equal if they contain the same (key,
@@ -273,9 +274,10 @@
     \sa operator!=()
 */
 
-/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::operator!=(const QMultiMap<Key, T> &other) const
+/*! \fn template<class Key, class T> bool operator!=(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)
+    \relates QMultiMap
 
-    Returns \c true if \a other is not equal to this multi map; otherwise
+    Returns \c true if \a lhs is not equal to \a rhs; otherwise
     returns \c false.
 
     Two multi maps are considered equal if they contain the same (key,
@@ -411,7 +413,7 @@
     items for \a key in the multi map, the value of the most recently
     inserted one is returned.
 
-    \sa key(), values(), contains(), operator[]()
+    \sa key(), values(), contains()
 */
 
 /*! \fn template <class Key, class T> QList<Key> QMultiMap<Key, T>::keys() const
@@ -819,7 +821,7 @@
     \sa replace()
 */
 
-/*! \fn [qmultimap-insert-pos] template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insert(const_iterator pos, const Key &key, const T &value)
+/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insert(const_iterator pos, const Key &key, const T &value)
     \overload
     \since 5.1
     Inserts a new item with the key \a key and value \a value and with hint \a pos
@@ -842,21 +844,35 @@
     crash but there is also a risk that it will silently corrupt both the multi map and the \a pos multi map.
 */
 
+#if QT_DEPRECATED_SINCE(6, 0)
 /*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insertMulti(const Key &key, const T &value)
+    \obsolete Use insert() instead.
 
-    Same as insert().
+    Inserts a new item with the key \a key and a value of \a value, and returns an iterator pointing to the new item.
 */
 
 /*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insertMulti(const_iterator pos, const Key &key, const T &value)
+    \obsolete Use insert() instead.
     \overload
 
-    Same as insert().
+    Inserts a new item with the key \a key and value \a value and with hint \a pos
+    suggesting where to do the insert.
 */
 
 /*! \fn template <class Key, class T> void QMultiMap<Key, T>::insert(const QMultiMap<Key, T> &map)
     \since 5.15
+    \obsolete Use unite() instead.
 
-    Same as unite().
+    Inserts all the items in \a map into this map.
+*/
+#endif
+
+/*! \fn template <class Key, class T> void QMultiMap<Key, T>::insert(QMultiMap<Key, T> &&map)
+    \since 5.15
+
+    Moves all the items from \a map into this map.
+
+    If \a map is shared, then the items will be copied instead.
 */
 
 /*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::replace(const Key &key, const T &value)
@@ -924,25 +940,25 @@
 */
 
 /*!
-    \fn [qmultimap-unite] template <class Key, class T> QMultiMap<Key, T> &QMultiMap<Key, T>::unite(const QMultiMap<Key, T> &other)
+    \fn template <class Key, class T> QMultiMap<Key, T> &QMultiMap<Key, T>::unite(const QMultiMap<Key, T> &other)
 
     Inserts all the items in the \a other map into this map. If a
     key is common to both maps, the resulting map will contain the
     key multiple times.
 */
 
-/*! \fn template <class Key, class T> QMultiMap &QMultiMap<Key, T>::operator+=(const QMultiMap &other)
+/*! \fn template <class Key, class T> QMultiMap<Key, T> operator+=(QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)
 
-    Inserts all the items in the \a other map into this map and
-    returns a reference to this map.
+    Inserts all the items in the \a rhs map into the \a lhs map and
+    returns the resulting map.
 
     \sa insert(), operator+()
 */
 
-/*! \fn template <class Key, class T> QMultiMap QMultiMap<Key, T>::operator+(const QMultiMap &other) const
+/*! \fn template <class Key, class T> QMultiMap<Key, T> operator+(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)
 
-    Returns a map that contains all the items in this map in
-    addition to all the items in \a other. If a key is common to both
+    Returns a map that contains all the items in the \a lhs map in
+    addition to all the items in \a rhs. If a key is common to both
     maps, the resulting map will contain the key multiple times.
 
     \sa operator+=()
@@ -1094,21 +1110,21 @@
 */
 
 /*!
-    \fn template <class Key, class T> bool QMultiMap<Key, T>::iterator::operator==(const iterator &other) const
-    \fn template <class Key, class T> bool QMultiMap<Key, T>::iterator::operator==(const const_iterator &other) const
+    \fn template<class Key, class T> bool QMultiMap<Key, T>::iterator::operator==(const iterator &lhs, const iterator &rhs)
+    \fn template<class Key, class T> bool QMultiMap<Key, T>::const_iterator::operator==(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to the same item as this
-    iterator; otherwise returns \c false.
+    Returns \c true if \a lhs points to the same item as the \a rhs iterator;
+    otherwise returns \c false.
 
     \sa operator!=()
 */
 
 /*!
-    \fn template <class Key, class T> bool QMultiMap<Key, T>::iterator::operator!=(const iterator &other) const
-    \fn template <class Key, class T> bool QMultiMap<Key, T>::iterator::operator!=(const const_iterator &other) const
+    \fn template<class Key, class T> bool QMultiMap<Key, T>::iterator::operator!=(const iterator &lhs, const iterator &rhs)
+    \fn template<class Key, class T> bool QMultiMap<Key, T>::const_iterator::operator!=(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to a different item than this
-    iterator; otherwise returns \c false.
+    Returns \c true if \a lhs points to a different item than the \a rhs iterator;
+    otherwise returns \c false.
 
     \sa operator==()
 */
@@ -1269,22 +1285,6 @@
     \sa value()
 */
 
-/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::const_iterator::operator==(const const_iterator &other) const
-
-    Returns \c true if \a other points to the same item as this
-    iterator; otherwise returns \c false.
-
-    \sa operator!=()
-*/
-
-/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::const_iterator::operator!=(const const_iterator &other) const
-
-    Returns \c true if \a other points to a different item than this
-    iterator; otherwise returns \c false.
-
-    \sa operator==()
-*/
-
 /*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator &QMultiMap<Key, T>::const_iterator::operator++()
 
     The prefix ++ operator (\c{++i}) advances the iterator to the