diff --git a/cmd/prometheus/main.go b/cmd/prometheus/main.go
index 763911363b..ad9108a6df 100644
--- a/cmd/prometheus/main.go
+++ b/cmd/prometheus/main.go
@@ -269,6 +269,7 @@ func (c *flagConfig) setFeatureListOptions(logger *slog.Logger) error {
 			case "created-timestamp-zero-ingestion":
 				// NOTE(bwplotka): Once AppendableV1 is removed, there will be only the TSDB and agent flags.
 				c.scrape.EnableStartTimestampZeroIngestion = true
+				c.scrape.ParseST = true
 				c.web.STZeroIngestionEnabled = true
 				c.tsdb.EnableSTAsZeroSample = true
 				c.agent.EnableSTAsZeroSample = true
@@ -280,6 +281,7 @@ func (c *flagConfig) setFeatureListOptions(logger *slog.Logger) error {
 				logger.Info("Experimental start timestamp zero ingestion enabled. Changed default scrape_protocols to prefer PrometheusProto format.", "global.scrape_protocols", fmt.Sprintf("%v", config.DefaultGlobalConfig.ScrapeProtocols))
 			case "st-storage":
 				// TODO(bwplotka): Implement ST Storage as per PROM-60 and document this hidden feature flag.
+				c.scrape.ParseST = true
 				c.tsdb.EnableSTStorage = true
 				c.agent.EnableSTStorage = true
 
diff --git a/scrape/manager.go b/scrape/manager.go
index 24a63b056b..17f7b804a3 100644
--- a/scrape/manager.go
+++ b/scrape/manager.go
@@ -115,8 +115,19 @@ type Options struct {
 
 	// Option to enable the ingestion of the created timestamp as a synthetic zero sample.
 	// See: https://github.com/prometheus/proposals/blob/main/proposals/2023-06-13_created-timestamp.md
+	//
+	// NOTE: This option has no effect for AppenderV2 and will be removed with the AppenderV1
+	// removal.
 	EnableStartTimestampZeroIngestion bool
 
+	// ParseST controls if ST should be parsed and appended from the scrape format
+	// notably from the expensive OpenMetrics 1.0 _created line flow. This adds some
+	// overhead and can yield wrong ST values on OM1 edge cases.
+	//
+	// This only applies to AppenderV2 flow.
+	// TODO: Move this option to OM1 parser and use only on OM1 flow
+	ParseST bool
+
 	// EnableTypeAndUnitLabels represents type-and-unit-labels feature flag.
 	EnableTypeAndUnitLabels bool
 
diff --git a/scrape/manager_test.go b/scrape/manager_test.go
index 395cc98a82..137596151b 100644
--- a/scrape/manager_test.go
+++ b/scrape/manager_test.go
@@ -767,6 +767,7 @@ func TestManagerSTZeroIngestion(t *testing.T) {
 							app := teststorage.NewAppendable()
 							discoveryManager, scrapeManager := runManagers(t, ctx, &Options{
 								EnableStartTimestampZeroIngestion: testSTZeroIngest,
+								ParseST:                           testSTZeroIngest,
 								skipOffsetting:                    true,
 							}, app, nil)
 							defer scrapeManager.Stop()
@@ -953,6 +954,7 @@ func TestManagerSTZeroIngestionHistogram(t *testing.T) {
 			app := teststorage.NewAppendable()
 			discoveryManager, scrapeManager := runManagers(t, ctx, &Options{
 				EnableStartTimestampZeroIngestion: tc.enableSTZeroIngestion,
+				ParseST:                           tc.enableSTZeroIngestion,
 				skipOffsetting:                    true,
 			}, app, nil)
 			defer scrapeManager.Stop()
@@ -1065,6 +1067,7 @@ func TestNHCBAndSTZeroIngestion(t *testing.T) {
 	app := teststorage.NewAppendable()
 	discoveryManager, scrapeManager := runManagers(t, ctx, &Options{
 		EnableStartTimestampZeroIngestion: true,
+		ParseST:                           true,
 		skipOffsetting:                    true,
 	}, app, nil)
 	defer scrapeManager.Stop()
diff --git a/scrape/scrape.go b/scrape/scrape.go
index d5a9ba72b4..cd102a23ba 100644
--- a/scrape/scrape.go
+++ b/scrape/scrape.go
@@ -870,6 +870,7 @@ type scrapeLoop struct {
 
 	// Options from scrape.Options.
 	enableSTZeroIngestion   bool
+	parseST                 bool // Used by AppenderV2 only.
 	enableTypeAndUnitLabels bool
 	reportExtraMetrics      bool
 	appendMetadataToWAL     bool
@@ -1223,7 +1224,12 @@ func newScrapeLoop(opts scrapeLoopOptions) *scrapeLoop {
 		validationScheme:              opts.sp.config.MetricNameValidationScheme,
 
 		// scrape.Options.
-		enableSTZeroIngestion:   opts.sp.options.EnableStartTimestampZeroIngestion,
+		enableSTZeroIngestion: opts.sp.options.EnableStartTimestampZeroIngestion,
+		// parseST was added recently. Before EnableStartTimestampZeroIngestion
+		// was enabling parsing ST. For non-Prometheus users of the scrape
+		// manager, we ensure appenderV2 parseST is set on EnableStartTimestampZeroIngestion
+		// This will be removed when EnableStartTimestampZeroIngestion is removed.
+		parseST:                 opts.sp.options.ParseST || opts.sp.options.EnableStartTimestampZeroIngestion,
 		enableTypeAndUnitLabels: opts.sp.options.EnableTypeAndUnitLabels,
 		appendMetadataToWAL:     opts.sp.options.AppendMetadata,
 		passMetadataInContext:   opts.sp.options.PassMetadataInContext,
diff --git a/scrape/scrape_append_v2.go b/scrape/scrape_append_v2.go
index 64969707e1..825e56f9df 100644
--- a/scrape/scrape_append_v2.go
+++ b/scrape/scrape_append_v2.go
@@ -102,7 +102,7 @@ func (sl *scrapeLoopAppenderV2) append(b []byte, contentType string, ts time.Tim
 		IgnoreNativeHistograms:                  !sl.enableNativeHistogramScraping,
 		ConvertClassicHistogramsToNHCB:          sl.convertClassicHistToNHCB,
 		KeepClassicOnClassicAndNativeHistograms: sl.alwaysScrapeClassicHist,
-		OpenMetricsSkipSTSeries:                 sl.enableSTZeroIngestion,
+		OpenMetricsSkipSTSeries:                 sl.parseST,
 		FallbackContentType:                     sl.fallbackScrapeProtocol,
 	})
 	if p == nil {
@@ -254,7 +254,7 @@ loop:
 			}
 
 			st := int64(0)
-			if sl.enableSTZeroIngestion {
+			if sl.parseST {
 				// p.StartTimestamp() tend to be expensive (e.g. OM1). Do it only if we care.
 				st = p.StartTimestamp()
 			}