diff --git a/server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java
index a0c605b750bef..a64e1675f12fa 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java
@@ -17,7 +17,6 @@
 import org.elasticsearch.common.Explicit;
 import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.logging.DeprecationLogger;
-import org.elasticsearch.common.util.FeatureFlag;
 import org.elasticsearch.common.xcontent.support.XContentMapValues;
 import org.elasticsearch.core.Nullable;
 import org.elasticsearch.features.NodeFeature;
@@ -49,7 +48,6 @@
 public class ObjectMapper extends Mapper {
     private static final Logger logger = LogManager.getLogger(ObjectMapper.class);
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(ObjectMapper.class);
-    public static final boolean SUB_OBJECTS_AUTO_FEATURE_FLAG = new FeatureFlag("sub_objects_auto").isEnabled();
     static final NodeFeature SUBOBJECTS_FALSE_MAPPING_UPDATE_FIX = new NodeFeature("mapper.subobjects_false_mapping_update_fix");
 
     public static final String CONTENT_TYPE = "object";
diff --git a/test/test-clusters/src/main/java/org/elasticsearch/test/cluster/FeatureFlag.java b/test/test-clusters/src/main/java/org/elasticsearch/test/cluster/FeatureFlag.java
index 527d961197e8a..6f0e04a215a35 100644
--- a/test/test-clusters/src/main/java/org/elasticsearch/test/cluster/FeatureFlag.java
+++ b/test/test-clusters/src/main/java/org/elasticsearch/test/cluster/FeatureFlag.java
@@ -17,7 +17,6 @@
  */
 public enum FeatureFlag {
     TIME_SERIES_MODE("es.index_mode_feature_flag_registered=true", Version.fromString("8.0.0"), null),
-    SUB_OBJECTS_AUTO_ENABLED("es.sub_objects_auto_feature_flag_enabled=true", Version.fromString("8.16.0"), null),
     DOC_VALUES_SKIPPER("es.doc_values_skipper_feature_flag_enabled=true", Version.fromString("8.18.1"), null),
     LOGS_STREAM("es.logs_stream_feature_flag_enabled=true", Version.fromString("9.1.0"), null),
     SYNTHETIC_VECTORS("es.mapping_synthetic_vectors=true", Version.fromString("9.2.0"), null),