diff --git a/pkg/api/pod/util.go b/pkg/api/pod/util.go
index 36f2e869f9f..621438091b2 100644
--- a/pkg/api/pod/util.go
+++ b/pkg/api/pod/util.go
@@ -416,6 +416,8 @@ func GetValidationOptionsFromPodSpecAndMeta(podSpec, oldPodSpec *api.PodSpec, po
 		}
 
 		opts.AllowPodLifecycleSleepActionZeroValue = opts.AllowPodLifecycleSleepActionZeroValue || podLifecycleSleepActionZeroValueInUse(podSpec)
+		// If oldPod has resize policy set on the restartable init container, we must allow it
+		opts.AllowSidecarResizePolicy = hasRestartableInitContainerResizePolicy(oldPodSpec)
 	}
 	if oldPodMeta != nil && !opts.AllowInvalidPodDeletionCost {
 		// This is an update, so validate only if the existing object was valid.
@@ -1373,3 +1375,17 @@ func useOnlyRecursiveSELinuxChangePolicy(oldPodSpec *api.PodSpec) bool {
 	// No feature gate + no value in the old object -> only Recursive is allowed
 	return true
 }
+
+// hasRestartableInitContainerResizePolicy returns true if the pod spec is non-nil and
+// it has any init container with ContainerRestartPolicyAlways and non-nil ResizePolicy.
+func hasRestartableInitContainerResizePolicy(podSpec *api.PodSpec) bool {
+	if podSpec == nil {
+		return false
+	}
+	for _, c := range podSpec.InitContainers {
+		if IsRestartableInitContainer(&c) && len(c.ResizePolicy) > 0 {
+			return true
+		}
+	}
+	return false
+}
diff --git a/pkg/api/pod/util_test.go b/pkg/api/pod/util_test.go
index 2f2f58e3f81..2f53c8fdc6e 100644
--- a/pkg/api/pod/util_test.go
+++ b/pkg/api/pod/util_test.go
@@ -4036,3 +4036,171 @@ func TestDropSELinuxChangePolicy(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateAllowSidecarResizePolicy(t *testing.T) {
+	restartPolicyAlways := api.ContainerRestartPolicyAlways
+	testCases := []struct {
+		name       string
+		oldPodSpec *api.PodSpec
+		wantOption bool
+	}{
+		{
+			name:       "old pod spec is nil",
+			wantOption: false,
+		},
+		{
+			name: "one sidecar container + one regular init container, no resize policy set on any of them",
+			oldPodSpec: &api.PodSpec{
+				InitContainers: []api.Container{
+					{
+						Name:          "c1-restartable-init",
+						Image:         "image",
+						RestartPolicy: &restartPolicyAlways,
+					},
+					{
+						Name:  "c1-init",
+						Image: "image",
+					},
+				},
+			},
+			wantOption: false,
+		},
+		{
+			name: "one sidecar container + one regular init container, resize policy set on regular init container",
+			oldPodSpec: &api.PodSpec{
+				InitContainers: []api.Container{
+					{
+						Name:          "c1-restartable-init",
+						Image:         "image",
+						RestartPolicy: &restartPolicyAlways,
+					},
+					{
+						Name:  "c1-init",
+						Image: "image",
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+				},
+			},
+			wantOption: false,
+		},
+		{
+			name: "one sidecar container + one regular init container, resize policy set on sidecar container",
+			oldPodSpec: &api.PodSpec{
+				InitContainers: []api.Container{
+					{
+						Name:          "c1-restartable-init",
+						Image:         "image",
+						RestartPolicy: &restartPolicyAlways,
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+					{
+						Name:  "c1-init",
+						Image: "image",
+					},
+				},
+			},
+			wantOption: true,
+		},
+		{
+			name: "one sidecar container + one regular init container, resize policy set on both of them",
+			oldPodSpec: &api.PodSpec{
+				InitContainers: []api.Container{
+					{
+						Name:          "c1-restartable-init",
+						Image:         "image",
+						RestartPolicy: &restartPolicyAlways,
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+					{
+						Name:  "c1-init",
+						Image: "image",
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+				},
+			},
+			wantOption: true,
+		},
+		{
+			name: "two sidecar containers, resize policy set on one of them",
+			oldPodSpec: &api.PodSpec{
+				InitContainers: []api.Container{
+					{
+						Name:          "c1-restartable-init",
+						Image:         "image",
+						RestartPolicy: &restartPolicyAlways,
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+					{
+						Name:          "c2-restartable-init",
+						Image:         "image",
+						RestartPolicy: &restartPolicyAlways,
+					},
+				},
+			},
+			wantOption: true,
+		},
+		{
+			name: "two regular init containers, resize policy set on both of them",
+			oldPodSpec: &api.PodSpec{
+				InitContainers: []api.Container{
+					{
+						Name:  "c1-init",
+						Image: "image",
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+					{
+						Name:  "c2-init",
+						Image: "image",
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+				},
+			},
+			wantOption: false,
+		},
+		{
+			name: "two non-init containers, resize policy set on both of them",
+			oldPodSpec: &api.PodSpec{
+				Containers: []api.Container{
+					{
+						Name:  "c1",
+						Image: "image",
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+					{
+						Name:  "c2",
+						Image: "image",
+						ResizePolicy: []api.ContainerResizePolicy{
+							{ResourceName: api.ResourceCPU, RestartPolicy: api.NotRequired},
+						},
+					},
+				},
+			},
+			wantOption: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			gotOptions := GetValidationOptionsFromPodSpecAndMeta(&api.PodSpec{}, tc.oldPodSpec, nil, nil)
+			if tc.wantOption != gotOptions.AllowSidecarResizePolicy {
+				t.Errorf("Got AllowSidecarResizePolicy=%t, want %t", gotOptions.AllowSidecarResizePolicy, tc.wantOption)
+			}
+		})
+	}
+}
diff --git a/pkg/apis/core/validation/validation.go b/pkg/apis/core/validation/validation.go
index d53d7fc010b..dfebbf43daf 100644
--- a/pkg/apis/core/validation/validation.go
+++ b/pkg/apis/core/validation/validation.go
@@ -3543,7 +3543,7 @@ func validateInitContainers(containers []core.Container, regularContainers []cor
 			}
 		}
 
-		if len(ctr.ResizePolicy) > 0 {
+		if !opts.AllowSidecarResizePolicy && len(ctr.ResizePolicy) > 0 {
 			allErrs = append(allErrs, field.Invalid(idxPath.Child("resizePolicy"), ctr.ResizePolicy, "must not be set for init containers"))
 		}
 	}
@@ -4051,6 +4051,8 @@ type PodValidationOptions struct {
 	AllowOnlyRecursiveSELinuxChangePolicy bool
 	// Indicates whether PodLevelResources feature is enabled or disabled.
 	PodLevelResourcesEnabled bool
+	// Allow sidecar containers resize policy for backward compatibility
+	AllowSidecarResizePolicy bool
 }
 
 // validatePodMetadataAndSpec tests if required fields in the pod.metadata and pod.spec are set,