Enable authenticated media by default

docs/usage/configuration/config_documentation.md

@@ -1887,12 +1887,11 @@ Config options related to Synapse's media store.
 
 When set to true, all subsequent media uploads will be marked as authenticated, and will not be available over legacy
 unauthenticated media endpoints (`/_matrix/media/(r0|v3|v1)/download` and `/_matrix/media/(r0|v3|v1)/thumbnail`) - requests for authenticated media over these endpoints will result in a 404. All media, including authenticated media, will be available over the authenticated media endpoints `_matrix/client/v1/media/download` and `_matrix/client/v1/media/thumbnail`. Media uploaded prior to setting this option to true will still be available over the legacy endpoints. Note if the setting is switched to false
-after enabling, media marked as authenticated will be available over legacy endpoints. Defaults to false, but
-this will change to true in a future Synapse release.
+after enabling, media marked as authenticated will be available over legacy endpoints. Defaults to true (previously false).
 
 Example configuration:
 ```yaml
-enable_authenticated_media: true
+enable_authenticated_media: false
 ```
 ---
 ### `enable_media_repo`

synapse/config/repository.py

@@ -273,7 +273,7 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
             )
 
         self.enable_authenticated_media = config.get(
-            "enable_authenticated_media", False
+            "enable_authenticated_media", True
         )
 
     def generate_config_section(self, data_dir_path: str, **kwargs: Any) -> str: