diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/netty/NettyProperties.java b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/netty/NettyProperties.java
index 1f381468a303..06988375eb51 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/netty/NettyProperties.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/netty/NettyProperties.java
@@ -32,7 +32,7 @@ public class NettyProperties {
 	/**
 	 * Level of leak detection for reference-counted buffers.
 	 */
-	private LeakDetection leakDetection = LeakDetection.SIMPLE;
+	private LeakDetection leakDetection = null;
 
 	public LeakDetection getLeakDetection() {
 		return this.leakDetection;
diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json b/spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json
index 1d6f4247a102..08eda3a7cb08 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json
@@ -2107,7 +2107,8 @@
     },
     {
       "name": "spring.netty.leak-detection",
-      "defaultValue": "simple"
+      "description": "When null, fall back to Netty system default 'simple' or value of -Dio.netty.leakDetection.level. When set, this will overrride value of -Dio.netty.leakDetection.level",
+      "defaultValue": "null"
     },
     {
       "name": "spring.quartz.jdbc.comment-prefix",
@@ -3366,4 +3367,4 @@
       ]
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/netty/NettyPropertiesTests.java b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/netty/NettyPropertiesTests.java
deleted file mode 100644
index df23a8ecb18d..000000000000
--- a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/netty/NettyPropertiesTests.java
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * Copyright 2012-2021 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.boot.autoconfigure.netty;
-
-import io.netty.util.ResourceLeakDetector;
-import io.netty.util.ResourceLeakDetector.Level;
-import org.junit.jupiter.api.Test;
-
-import org.springframework.test.util.ReflectionTestUtils;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-/**
- * Tests for {@link NettyProperties}
- *
- * @author Brian Clozel
- */
-class NettyPropertiesTests {
-
-	@Test
-	void defaultValueShouldMatchNettys() {
-		NettyProperties properties = new NettyProperties();
-		ResourceLeakDetector.Level defaultLevel = (Level) ReflectionTestUtils.getField(ResourceLeakDetector.class,
-				"DEFAULT_LEVEL");
-		assertThat(ResourceLeakDetector.Level.valueOf(properties.getLeakDetection().name())).isEqualTo(defaultLevel);
-	}
-
-}