diff --git a/UPGRADE.md b/UPGRADE.md
index 83f1658789c..af74354f2d4 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -8,6 +8,18 @@ awareness about deprecated code.
 
 # Upgrade to 3.4
 
+## Deprecated transaction nesting without savepoints
+
+Starting a transaction inside another transaction with
+`Doctrine\DBAL\Connection::beginTransaction()` without enabling transaction
+nesting with savepoints beforehand is deprecated.
+
+Transaction nesting with savepoints can be enabled with
+`$connection->setNestTransactionsWithSavepoints(true);`
+
+In case your platform does not support savepoints, you will have to rework your
+application logic so as to avoid nested transaction blocks.
+
 ## Added runtime deprecations for the default string column length.
 
 In addition to the formal deprecation introduced in DBAL 3.2, the library will now emit a deprecation message at runtime
diff --git a/docs/en/reference/transactions.rst b/docs/en/reference/transactions.rst
index 30bcd1049aa..5dc03048e0d 100644
--- a/docs/en/reference/transactions.rst
+++ b/docs/en/reference/transactions.rst
@@ -77,8 +77,15 @@ disabled. The value for that setting can be set on a per-connection
 basis, with
 ``Doctrine\DBAL\Connection#setNestTransactionsWithSavepoints()``.
 
+Nesting transactions without savepoints is deprecated, but is the
+default behavior for backward compatibility reasons.
+
 Dummy mode
 ~~~~~~~~~~
+.. warning::
+
+    This behavior is deprecated, avoid it with
+    ``Doctrine\DBAL\Connection#setNestTransactionsWithSavepoints(true)``.
 
 When transaction nesting with savepoints is disabled, what happens is
 not so much transaction nesting as propagating transaction control up
diff --git a/src/Connection.php b/src/Connection.php
index 4db448ec1ef..f7ca639cba5 100644
--- a/src/Connection.php
+++ b/src/Connection.php
@@ -1251,6 +1251,18 @@ public function transactional(Closure $func)
      */
     public function setNestTransactionsWithSavepoints($nestTransactionsWithSavepoints)
     {
+        if (! $nestTransactionsWithSavepoints) {
+            Deprecation::trigger(
+                'doctrine/dbal',
+                'https://github.com/doctrine/dbal/pull/5383',
+                <<<'DEPRECATION'
+                Nesting transactions without enabling savepoints is deprecated.
+                Call %s::setNestTransactionsWithSavepoints(true) to enable savepoints.
+                DEPRECATION,
+                self::class
+            );
+        }
+
         if ($this->transactionNestingLevel > 0) {
             throw ConnectionException::mayNotAlterNestedTransactionWithSavepointsInTransaction();
         }
@@ -1314,6 +1326,16 @@ public function beginTransaction()
             if ($logger !== null) {
                 $logger->stopQuery();
             }
+        } else {
+            Deprecation::trigger(
+                'doctrine/dbal',
+                'https://github.com/doctrine/dbal/pull/5383',
+                <<<'DEPRECATION'
+                Nesting transactions without enabling savepoints is deprecated.
+                Call %s::setNestTransactionsWithSavepoints(true) to enable savepoints.
+                DEPRECATION,
+                self::class
+            );
         }
 
         $this->getEventManager()->dispatchEvent(Events::onTransactionBegin, new TransactionBeginEventArgs($this));
diff --git a/tests/ConnectionTest.php b/tests/ConnectionTest.php
index 58147d40ebe..533493bc237 100644
--- a/tests/ConnectionTest.php
+++ b/tests/ConnectionTest.php
@@ -22,6 +22,7 @@
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Result;
 use Doctrine\DBAL\VersionAwarePlatformDriver;
+use Doctrine\Deprecations\PHPUnit\VerifyDeprecations;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Psr\Cache\CacheItemInterface;
@@ -33,6 +34,8 @@
  */
 class ConnectionTest extends TestCase
 {
+    use VerifyDeprecations;
+
     /** @var Connection */
     private $connection;
 
@@ -900,6 +903,12 @@ public function testExecuteCacheQueryStripsPlatformFromConnectionParamsBeforeGen
 
         $connection->executeCacheQuery($query, [], [], $queryCacheProfile);
     }
+
+    public function testNestingTransactionsWithoutSavepointsIsDeprecated(): void
+    {
+        $this->expectDeprecationWithIdentifier('https://github.com/doctrine/dbal/pull/5383');
+        $this->connection->setNestTransactionsWithSavepoints(false);
+    }
 }
 
 interface ConnectDispatchEventListener
diff --git a/tests/Functional/ConnectionTest.php b/tests/Functional/ConnectionTest.php
index 1f593284584..06f2afd0d5b 100644
--- a/tests/Functional/ConnectionTest.php
+++ b/tests/Functional/ConnectionTest.php
@@ -19,6 +19,7 @@
 use Doctrine\DBAL\Tests\FunctionalTestCase;
 use Doctrine\DBAL\Tests\TestUtil;
 use Doctrine\DBAL\Types\Types;
+use Doctrine\Deprecations\PHPUnit\VerifyDeprecations;
 use Error;
 use PDO;
 use Throwable;
@@ -28,6 +29,8 @@
 
 class ConnectionTest extends FunctionalTestCase
 {
+    use VerifyDeprecations;
+
     private const TABLE = 'connection_test';
 
     protected function tearDown(): void
@@ -62,6 +65,7 @@ public function testTransactionNestingBehavior(): void
             self::assertSame(1, $this->connection->getTransactionNestingLevel());
 
             try {
+                $this->expectDeprecationWithIdentifier('https://github.com/doctrine/dbal/pull/5383');
                 $this->connection->beginTransaction();
                 self::assertSame(2, $this->connection->getTransactionNestingLevel());