diff --git a/internal/resources/grafana/resource_data_source.go b/internal/resources/grafana/resource_data_source.go
index d5d6f0bcf..45bd7ab75 100644
--- a/internal/resources/grafana/resource_data_source.go
+++ b/internal/resources/grafana/resource_data_source.go
@@ -245,13 +245,16 @@ func CreateDataSource(ctx context.Context, d *schema.ResourceData, meta any) dia
 		return diag.FromErr(err)
 	}
 
+	diags := checkDeprecatedPrometheusAuth(d)
+
 	resp, err := client.Datasources.AddDataSource(dataSource)
 	if err != nil {
 		return diag.FromErr(err)
 	}
 
 	d.SetId(MakeOrgResourceID(orgID, resp.Payload.Datasource.UID))
-	return ReadDataSource(ctx, d, meta)
+	readDiags := ReadDataSource(ctx, d, meta)
+	return append(diags, readDiags...)
 }
 
 // UpdateDataSource updates a Grafana datasource
@@ -262,6 +265,9 @@ func UpdateDataSource(ctx context.Context, d *schema.ResourceData, meta any) dia
 	if err != nil {
 		return diag.FromErr(err)
 	}
+
+	diags := checkDeprecatedPrometheusAuth(d)
+
 	body := models.UpdateDataSourceCommand{
 		Access:          dataSource.Access,
 		BasicAuth:       dataSource.BasicAuth,
@@ -279,7 +285,11 @@ func UpdateDataSource(ctx context.Context, d *schema.ResourceData, meta any) dia
 	}
 	_, err = client.Datasources.UpdateDataSourceByUID(idStr, &body)
 
-	return diag.FromErr(err)
+	if err != nil {
+		return append(diags, diag.FromErr(err)...)
+	}
+
+	return diags
 }
 
 // ReadDataSource reads a Grafana datasource
@@ -450,3 +460,42 @@ func removeHeadersFromJSONData(input map[string]any) (map[string]any, map[string
 
 	return jsonData, headers
 }
+
+// checkDeprecatedPrometheusAuth checks if the data source is using deprecated authentication methods
+func checkDeprecatedPrometheusAuth(d *schema.ResourceData) diag.Diagnostics {
+	var diags diag.Diagnostics
+
+	dsType := d.Get("type").(string)
+	if dsType != "prometheus" {
+		return diags
+	}
+
+	jsonDataEncoded := d.Get("json_data_encoded").(string)
+	if jsonDataEncoded == "" {
+		return diags
+	}
+
+	var jsonData map[string]any
+	if err := json.Unmarshal([]byte(jsonDataEncoded), &jsonData); err != nil {
+		// If we can't parse it, don't add a warning
+		return diags
+	}
+
+	if sigV4Auth, ok := jsonData["sigV4Auth"].(bool); ok && sigV4Auth {
+		diags = append(diags, diag.Diagnostic{
+			Severity: diag.Warning,
+			Summary:  "Deprecated authentication method",
+			Detail:   "SigV4 authentication is deprecated for the core Prometheus data source. Please install Amazon Managed Service for Prometheus found here: https://grafana.com/grafana/plugins/grafana-amazonprometheus-datasource/ and then change the type of your data source to 'grafana-amazonprometheus-datasource'.",
+		})
+	}
+
+	if azureAuth, ok := jsonData["azureCredentials"]; ok && azureAuth != nil {
+		diags = append(diags, diag.Diagnostic{
+			Severity: diag.Warning,
+			Summary:  "Deprecated authentication method",
+			Detail:   "Azure authentication is deprecated for the core Prometheus data source. lease install Amazon Managed Service for Prometheus found here: https://grafana.com/grafana/plugins/grafana-azureprometheus-datasource/ and then change the type of your data source to 'grafana-azureprometheus-datasource'.",
+		})
+	}
+
+	return diags
+}
diff --git a/internal/resources/grafana/resource_data_source_deprecated_auth_test.go b/internal/resources/grafana/resource_data_source_deprecated_auth_test.go
new file mode 100644
index 000000000..2c3f719f4
--- /dev/null
+++ b/internal/resources/grafana/resource_data_source_deprecated_auth_test.go
@@ -0,0 +1,70 @@
+package grafana
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCheckDeprecatedPrometheusAuth_SigV4(t *testing.T) {
+	d := schema.TestResourceDataRaw(t, resourceDataSource().Schema.Schema, map[string]interface{}{
+		"name":              "test-prometheus",
+		"type":              "prometheus",
+		"url":               "http://localhost:9090",
+		"json_data_encoded": `{"sigV4Auth":true}`,
+	})
+
+	diags := checkDeprecatedPrometheusAuth(d)
+
+	if len(diags) != 1 {
+		t.Errorf("Expected 1 diagnostic, got %d", len(diags))
+	}
+
+	require.Equal(t, len(diags), 1)
+	require.Equal(t, diags[0].Severity, diag.Warning)
+}
+
+func TestCheckDeprecatedPrometheusAuth_Azure(t *testing.T) {
+	d := schema.TestResourceDataRaw(t, resourceDataSource().Schema.Schema, map[string]interface{}{
+		"name":              "test-prometheus",
+		"type":              "prometheus",
+		"url":               "http://localhost:9090",
+		"json_data_encoded": `{"azureCredentials":{}}`,
+	})
+
+	diags := checkDeprecatedPrometheusAuth(d)
+
+	if len(diags) != 1 {
+		t.Errorf("Expected 1 diagnostic, got %d", len(diags))
+	}
+
+	require.Equal(t, len(diags), 1)
+	require.Equal(t, diags[0].Severity, diag.Warning)
+}
+
+func TestCheckDeprecatedPrometheusAuth_NoDeprecatedAuth(t *testing.T) {
+	d := schema.TestResourceDataRaw(t, resourceDataSource().Schema.Schema, map[string]interface{}{
+		"name": "test-prometheus",
+		"type": "prometheus",
+		"url":  "http://localhost:9090",
+	})
+
+	diags := checkDeprecatedPrometheusAuth(d)
+
+	require.Equal(t, len(diags), 0)
+}
+
+func TestCheckDeprecatedPrometheusAuth_NonPrometheusDataSource(t *testing.T) {
+	d := schema.TestResourceDataRaw(t, resourceDataSource().Schema.Schema, map[string]interface{}{
+		"name":              "test-loki",
+		"type":              "loki",
+		"url":               "http://localhost:9090",
+		"json_data_encoded": `{"sigV4Auth":true}`,
+	})
+
+	diags := checkDeprecatedPrometheusAuth(d)
+
+	require.Equal(t, len(diags), 0)
+}