diff --git a/docs/content/migrate/v3.md b/docs/content/migrate/v3.md
index 8f8194fef..82f11f66e 100644
--- a/docs/content/migrate/v3.md
+++ b/docs/content/migrate/v3.md
@@ -489,3 +489,10 @@ To use the new `proxyprotocol` option in the Kubernetes CRD provider, you need t
 ```shell
 kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.5/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml
 ```
+
+## v3.5.4
+
+### Certificate Metric Renamed with OpenTelemetry 
+
+Starting with `v3.5.4`, and when using OpenTelemetry, the `traefik_tls_certs_not_after_milliseconds` metric is renamed to `traefik_tls_certs_not_after_seconds`.
+This change aligns the metric name with its real unit precision, which is in seconds. 
diff --git a/pkg/observability/metrics/otel.go b/pkg/observability/metrics/otel.go
index cfb3f50ef..eaf95e736 100644
--- a/pkg/observability/metrics/otel.go
+++ b/pkg/observability/metrics/otel.go
@@ -125,7 +125,7 @@ func RegisterOpenTelemetry(ctx context.Context, config *otypes.OTLP) Registry {
 		configReloadsCounter:           newOTLPCounterFrom(meter, configReloadsTotalName, "Config reloads"),
 		lastConfigReloadSuccessGauge:   newOTLPGaugeFrom(meter, configLastReloadSuccessName, "Last config reload success", "ms"),
 		openConnectionsGauge:           newOTLPGaugeFrom(meter, openConnectionsName, "How many open connections exist, by entryPoint and protocol", "1"),
-		tlsCertsNotAfterTimestampGauge: newOTLPGaugeFrom(meter, tlsCertsNotAfterTimestampName, "Certificate expiration timestamp", "ms"),
+		tlsCertsNotAfterTimestampGauge: newOTLPGaugeFrom(meter, tlsCertsNotAfterTimestampName, "Certificate expiration timestamp", "s"),
 	}
 
 	if config.AddEntryPointsLabels {
diff --git a/pkg/observability/metrics/otel_test.go b/pkg/observability/metrics/otel_test.go
index 756f98ae8..abcb1856f 100644
--- a/pkg/observability/metrics/otel_test.go
+++ b/pkg/observability/metrics/otel_test.go
@@ -365,7 +365,7 @@ func TestOpenTelemetry(t *testing.T) {
 			tryAssertMessage(t, c, expectedConfig)
 
 			expectedTLSCerts := []string{
-				`({"name":"traefik_tls_certs_not_after","description":"Certificate expiration timestamp","unit":"ms","gauge":{"dataPoints":\[{"attributes":\[{"key":"key","value":{"stringValue":"value"}}\],"startTimeUnixNano":"[\d]{19}","timeUnixNano":"[\d]{19}","asDouble":1}\]}})`,
+				`({"name":"traefik_tls_certs_not_after","description":"Certificate expiration timestamp","unit":"s","gauge":{"dataPoints":\[{"attributes":\[{"key":"key","value":{"stringValue":"value"}}\],"startTimeUnixNano":"[\d]{19}","timeUnixNano":"[\d]{19}","asDouble":1}\]}})`,
 			}
 
 			registry.TLSCertsNotAfterTimestampGauge().With("key", "value").Set(1)