diff --git a/spring-core/src/main/java/org/springframework/aot/hint/support/RuntimeHintsUtils.java b/spring-core/src/main/java/org/springframework/aot/hint/support/RuntimeHintsUtils.java
index da88f675ba..6f687889a4 100644
--- a/spring-core/src/main/java/org/springframework/aot/hint/support/RuntimeHintsUtils.java
+++ b/spring-core/src/main/java/org/springframework/aot/hint/support/RuntimeHintsUtils.java
@@ -49,7 +49,6 @@ public abstract class RuntimeHintsUtils {
 	 * at runtime.
 	 * @param hints the {@link RuntimeHints} instance to use
 	 * @param annotationType the annotation type
-	 * @see SynthesizedAnnotation
 	 * @deprecated as annotation attributes are visible without additional hints
 	 */
 	@Deprecated
@@ -70,7 +69,6 @@ public abstract class RuntimeHintsUtils {
 	 * that determines if the hints are required.
 	 * @param hints the {@link RuntimeHints} instance to use
 	 * @param annotationType the annotation type
-	 * @see SynthesizedAnnotation
 	 */
 	public static void registerSynthesizedAnnotation(RuntimeHints hints, Class<?> annotationType) {
 		hints.proxies().registerJdkProxy(annotationType, SynthesizedAnnotation.class);
diff --git a/spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java b/spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java
index f42873522f..53add8a193 100644
--- a/spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java
+++ b/spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java
@@ -22,6 +22,7 @@ import java.lang.reflect.Array;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
+import java.lang.reflect.Proxy;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -1288,7 +1289,15 @@ public abstract class AnnotationUtils {
 	 * @since 5.3.23
 	 */
 	public static boolean isSynthesizedAnnotation(@Nullable Annotation annotation) {
-		return (annotation instanceof SynthesizedAnnotation);
+		try {
+			return ((annotation != null) && Proxy.isProxyClass(annotation.getClass()) &&
+					(Proxy.getInvocationHandler(annotation) instanceof SynthesizedMergedAnnotationInvocationHandler));
+		}
+		catch (SecurityException ex) {
+			// Security settings disallow reflective access to the InvocationHandler:
+			// assume the annotation has not been synthesized by Spring.
+			return false;
+		}
 	}
 
 	/**
diff --git a/spring-core/src/main/java/org/springframework/core/annotation/SynthesizedMergedAnnotationInvocationHandler.java b/spring-core/src/main/java/org/springframework/core/annotation/SynthesizedMergedAnnotationInvocationHandler.java
index 992b1a07fa..c8eaf22e41 100644
--- a/spring-core/src/main/java/org/springframework/core/annotation/SynthesizedMergedAnnotationInvocationHandler.java
+++ b/spring-core/src/main/java/org/springframework/core/annotation/SynthesizedMergedAnnotationInvocationHandler.java
@@ -299,9 +299,8 @@ final class SynthesizedMergedAnnotationInvocationHandler<A extends Annotation> i
 	@SuppressWarnings("unchecked")
 	static <A extends Annotation> A createProxy(MergedAnnotation<A> annotation, Class<A> type) {
 		ClassLoader classLoader = type.getClassLoader();
+		Class<?>[] interfaces = new Class<?>[] {type};
 		InvocationHandler handler = new SynthesizedMergedAnnotationInvocationHandler<>(annotation, type);
-		Class<?>[] interfaces = isVisible(classLoader, SynthesizedAnnotation.class) ?
-				new Class<?>[] {type, SynthesizedAnnotation.class} : new Class<?>[] {type};
 		return (A) Proxy.newProxyInstance(classLoader, interfaces, handler);
 	}
 
@@ -310,17 +309,4 @@ final class SynthesizedMergedAnnotationInvocationHandler<A extends Annotation> i
 		return (canonicalName != null ? canonicalName : clazz.getName());
 	}
 
-
-	private static boolean isVisible(ClassLoader classLoader, Class<?> interfaceClass) {
-		if (classLoader == interfaceClass.getClassLoader()) {
-			return true;
-		}
-		try {
-			return Class.forName(interfaceClass.getName(), false, classLoader) == interfaceClass;
-		}
-		catch (ClassNotFoundException ex) {
-			return false;
-		}
-	}
-
 }
diff --git a/spring-core/src/main/java/org/springframework/core/annotation/TypeMappedAnnotation.java b/spring-core/src/main/java/org/springframework/core/annotation/TypeMappedAnnotation.java
index 1fcbb18883..c2ae3a5dc7 100644
--- a/spring-core/src/main/java/org/springframework/core/annotation/TypeMappedAnnotation.java
+++ b/spring-core/src/main/java/org/springframework/core/annotation/TypeMappedAnnotation.java
@@ -363,7 +363,7 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 	 * @since 5.3.22
 	 */
 	private boolean isSynthesizable(Annotation annotation) {
-		if (annotation instanceof SynthesizedAnnotation) {
+		if (AnnotationUtils.isSynthesizedAnnotation(annotation)) {
 			return false;
 		}
 		return isSynthesizable();
diff --git a/spring-core/src/test/java/org/springframework/core/annotation/MergedAnnotationsTests.java b/spring-core/src/test/java/org/springframework/core/annotation/MergedAnnotationsTests.java
index 1f9ee30680..d97e10050b 100644
--- a/spring-core/src/test/java/org/springframework/core/annotation/MergedAnnotationsTests.java
+++ b/spring-core/src/test/java/org/springframework/core/annotation/MergedAnnotationsTests.java
@@ -1511,6 +1511,26 @@ class MergedAnnotationsTests {
 		assertThat(MergedAnnotation.from(component).isSynthesizable()).isFalse();
 	}
 
+	/**
+	 * @since 6.0
+	 */
+	@Test
+	void synthesizedAnnotationShouldReuseJdkProxyClass() throws Exception {
+		Method method = WebController.class.getMethod("handleMappedWithValueAttribute");
+
+		RequestMapping jdkRequestMapping = method.getAnnotation(RequestMapping.class);
+		assertThat(jdkRequestMapping).isNotNull();
+		assertThat(jdkRequestMapping.value()).containsExactly("/test");
+		assertThat(jdkRequestMapping.path()).containsExactly("");
+
+		RequestMapping synthesizedRequestMapping = MergedAnnotation.from(jdkRequestMapping).synthesize();
+		assertSynthesized(synthesizedRequestMapping);
+		assertThat(synthesizedRequestMapping.value()).containsExactly("/test");
+		assertThat(synthesizedRequestMapping.path()).containsExactly("/test");
+
+		assertThat(jdkRequestMapping.getClass()).isSameAs(synthesizedRequestMapping.getClass());
+	}
+
 	@Test
 	void synthesizeAlreadySynthesized() throws Exception {
 		Method method = WebController.class.getMethod("handleMappedWithValueAttribute");
@@ -1585,7 +1605,6 @@ class MergedAnnotationsTests {
 				mergedAnnotations.get(EnableGlobalAuthentication.class);
 		assertThat(enableGlobalAuthenticationMergedAnnotation.isSynthesizable()).isFalse();
 		EnableGlobalAuthentication enableGlobalAuthentication = enableGlobalAuthenticationMergedAnnotation.synthesize();
-		assertThat(enableGlobalAuthentication).isNotInstanceOf(SynthesizedAnnotation.class);
 		assertNotSynthesized(enableGlobalAuthentication);
 	}