diff --git a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/admission.go b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/admission.go
index 751c4753d72..fdc95aa9331 100644
--- a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/admission.go
+++ b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/admission.go
@@ -67,7 +67,7 @@ func (admit *managedFieldsValidatingAdmissionController) Admit(ctx context.Conte
 		return err
 	}
 	managedFieldsAfterAdmission := objectMeta.GetManagedFields()
-	if err := ValidateManagedFields(managedFieldsAfterAdmission); err != nil {
+	if _, err := DecodeManagedFields(managedFieldsAfterAdmission); err != nil {
 		objectMeta.SetManagedFields(managedFieldsBeforeAdmission)
 		warning.AddWarning(ctx, "",
 			fmt.Sprintf(InvalidManagedFieldsAfterMutatingAdmissionWarningFormat,
diff --git a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/validation.go b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/validation.go
deleted file mode 100644
index 324c23b5553..00000000000
--- a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/validation.go
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
-Copyright 2021 The Kubernetes 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
-
-    http://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 fieldmanager
-
-import (
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	v1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
-	"k8s.io/apimachinery/pkg/util/validation/field"
-)
-
-// ValidateManagedFields by checking the integrity of every entry and trying to decode
-// them to the internal format
-func ValidateManagedFields(managedFields []metav1.ManagedFieldsEntry) error {
-	validationErrs := v1validation.ValidateManagedFields(managedFields, field.NewPath("metadata").Child("managedFields"))
-	if len(validationErrs) > 0 {
-		return validationErrs.ToAggregate()
-	}
-
-	if _, err := DecodeManagedFields(managedFields); err != nil {
-		return err
-	}
-
-	return nil
-}
diff --git a/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go b/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go
index e6f9a9250f2..9a5ba8e8df3 100644
--- a/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go
+++ b/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go
@@ -34,7 +34,9 @@ import (
 	admissionv1 "k8s.io/api/admissionregistration/v1"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	v1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager"
 	clientset "k8s.io/client-go/kubernetes"
@@ -127,7 +129,7 @@ func TestMutatingWebhookResetsInvalidManagedFields(t *testing.T) {
 		if err != nil {
 			return false, err
 		}
-		if err := fieldmanager.ValidateManagedFields(pod.ManagedFields); err != nil {
+		if err := validateManagedFieldsAndDecode(pod.ManagedFields); err != nil {
 			lastErr = err
 			return false, nil
 		}
@@ -152,7 +154,7 @@ func TestMutatingWebhookResetsInvalidManagedFields(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if err := fieldmanager.ValidateManagedFields(pod.ManagedFields); err != nil {
+	if err := validateManagedFieldsAndDecode(pod.ManagedFields); err != nil {
 		t.Error(err)
 	}
 	if warningWriter.WarningCount() != 2 {
@@ -164,6 +166,16 @@ func TestMutatingWebhookResetsInvalidManagedFields(t *testing.T) {
 	}
 }
 
+// validate against both decoding and validation to make sure we use the hardest rule between the both to reset
+// with decoding being as strict as it gets, only using it should be enough in admission
+func validateManagedFieldsAndDecode(managedFields []metav1.ManagedFieldsEntry) error {
+	if _, err := fieldmanager.DecodeManagedFields(managedFields); err != nil {
+		return err
+	}
+	validationErrs := v1validation.ValidateManagedFields(managedFields, field.NewPath("metadata").Child("managedFields"))
+	return validationErrs.ToAggregate()
+}
+
 func newInvalidManagedFieldsWebhookHandler(t *testing.T) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()