diff --git a/generated/google-apis-discoveryengine_v1alpha/CHANGELOG.md b/generated/google-apis-discoveryengine_v1alpha/CHANGELOG.md
index 84a49c76fb4..14f3db23e47 100644
--- a/generated/google-apis-discoveryengine_v1alpha/CHANGELOG.md
+++ b/generated/google-apis-discoveryengine_v1alpha/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Release history for google-apis-discoveryengine_v1alpha
 
+### v0.88.0 (2025-12-28)
+
+* Regenerated from discovery document revision 20251221
+
 ### v0.87.0 (2025-12-21)
 
 * Regenerated from discovery document revision 20251217
diff --git a/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/gem_version.rb b/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/gem_version.rb
index 78af0f5db4b..0531a827bf6 100644
--- a/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/gem_version.rb
+++ b/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/gem_version.rb
@@ -16,13 +16,13 @@ module Google
   module Apis
     module DiscoveryengineV1alpha
       # Version of the google-apis-discoveryengine_v1alpha gem
-      GEM_VERSION = "0.87.0"
+      GEM_VERSION = "0.88.0"
 
       # Version of the code generator used to generate this client
       GENERATOR_VERSION = "0.18.0"
 
       # Revision of the discovery document this client was generated from
-      REVISION = "20251217"
+      REVISION = "20251221"
     end
   end
 end
diff --git a/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/service.rb b/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/service.rb
index bb4ba7e0051..efebed341b4 100644
--- a/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/service.rb
+++ b/generated/google-apis-discoveryengine_v1alpha/lib/google/apis/discoveryengine_v1alpha/service.rb
@@ -1278,11 +1278,12 @@ def patch_project_location_collection(name, google_cloud_discoveryengine_v1alpha
         # @param [Google::Apis::DiscoveryengineV1alpha::GoogleCloudDiscoveryengineV1alphaDataConnector] google_cloud_discoveryengine_v1alpha_data_connector_object
         # @param [String] update_mask
         #   Indicates which fields in the provided DataConnector to update. Supported
-        #   field paths include: - refresh_interval - params - auto_run_disabled -
-        #   action_config - action_config.action_params - action_config.service_name -
-        #   destination_configs - blocking_reasons - sync_mode - incremental_sync_disabled
-        #   - incremental_refresh_interval Note: Support for these fields may vary
-        #   depending on the connector type. For example, not all connectors support `
+        #   field paths include: - `refresh_interval` - `params` - `auto_run_disabled` - `
+        #   action_config` - `action_config.action_params` - `action_config.service_name` -
+        #   `destination_configs` - `blocking_reasons` - `sync_mode` - `
+        #   incremental_sync_disabled` - `incremental_refresh_interval` - `
+        #   data_protection_policy` Note: Support for these fields may vary depending on
+        #   the connector type. For example, not all connectors support `
         #   destination_configs`. If an unsupported or unknown field path is provided, the
         #   request will return an INVALID_ARGUMENT error.
         # @param [String] fields