diff --git a/config/initializers/lograge.rb b/config/initializers/lograge.rb
index 61e357808d9b190278afe415a9b96a0a5a3292c4..e5abc0b919bcfbc7734a2493c7962873f3c157bb 100644
--- a/config/initializers/lograge.rb
+++ b/config/initializers/lograge.rb
@@ -8,7 +8,7 @@
     Rails.application.configure do
       config.lograge.enabled = true
       # Store the lograge JSON files in a separate file
-      config.lograge.keep_original_rails_log = Gitlab::Utils.to_boolean(ENV.fetch('UNSTRUCTURED_RAILS_LOG', 'true'))
+      config.lograge.keep_original_rails_log = Gitlab::Utils.to_boolean(ENV.fetch('UNSTRUCTURED_RAILS_LOG', 'false'))
       # Don't use the Logstash formatter since this requires logstash-event, an
       # unmaintained gem that monkey patches `Time`
       config.lograge.formatter = Lograge::Formatters::Json.new
diff --git a/doc/administration/environment_variables.md b/doc/administration/environment_variables.md
index d2edc3085f13bf0744f7d38b1792f4b7ac1afe26..b6a3a563ae1fc022ee37cd9264867264cf767f2f 100644
--- a/doc/administration/environment_variables.md
+++ b/doc/administration/environment_variables.md
@@ -35,7 +35,7 @@ You can use the following environment variables to override certain values:
 | `GITLAB_ROOT_PASSWORD`                     | string  | Sets the password for the `root` user on installation.                                                  |
 | `GITLAB_SHARED_RUNNERS_REGISTRATION_TOKEN` | string  | Sets the initial registration token used for runners.                                                   |
 | `RAILS_ENV`                                | string  | The Rails environment; can be one of `production`, `development`, `staging`, or `test`.                 |
-| `UNSTRUCTURED_RAILS_LOG`                   | string  | Enables the unstructured log in addition to JSON logs (defaults to `true`).                             |
+| `UNSTRUCTURED_RAILS_LOG`                   | string  | Enables the unstructured log in addition to JSON logs (defaults to `false`).                             |
 | `GITLAB_RAILS_CACHE_DEFAULT_TTL_SECONDS` | integer | The default TTL used for entries stored in the Rails-cache. Default is `28800`. [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/95042) in 15.3. |
 
 ## Adding more variables
diff --git a/lib/gitlab/app_logger.rb b/lib/gitlab/app_logger.rb
index a39e7f318869f7bf3b0d9191df60afcbafddf0cd..40bdc5385940a3c46a99315e182f6aa5f5102133 100644
--- a/lib/gitlab/app_logger.rb
+++ b/lib/gitlab/app_logger.rb
@@ -5,7 +5,7 @@ class AppLogger < Gitlab::MultiDestinationLogger
     LOGGERS = [Gitlab::AppTextLogger, Gitlab::AppJsonLogger].freeze
 
     def self.loggers
-      if Gitlab::Utils.to_boolean(ENV.fetch('UNSTRUCTURED_RAILS_LOG', 'true'))
+      if Gitlab::Utils.to_boolean(ENV.fetch('UNSTRUCTURED_RAILS_LOG', 'false'))
         LOGGERS
       else
         [Gitlab::AppJsonLogger]
diff --git a/spec/lib/gitlab/app_logger_spec.rb b/spec/lib/gitlab/app_logger_spec.rb
index 85ca60d539f9262247ac9caff0577247203de69f..e3415f4ad8ca5aa9a22302210cf11d2abfb4f608 100644
--- a/spec/lib/gitlab/app_logger_spec.rb
+++ b/spec/lib/gitlab/app_logger_spec.rb
@@ -5,22 +5,27 @@
 RSpec.describe Gitlab::AppLogger do
   subject { described_class }
 
-  it 'builds two Logger instances' do
-    expect(Gitlab::Logger).to receive(:new).and_call_original
-    expect(Gitlab::JsonLogger).to receive(:new).and_call_original
+  context 'when UNSTRUCTURED_RAILS_LOG is enabled' do
+    before do
+      stub_env('UNSTRUCTURED_RAILS_LOG', 'true')
+    end
 
-    subject.info('Hello World!')
-  end
+    it 'builds two Logger instances' do
+      expect(Gitlab::Logger).to receive(:new).and_call_original
+      expect(Gitlab::JsonLogger).to receive(:new).and_call_original
 
-  it 'logs info to AppLogger and AppJsonLogger' do
-    expect_any_instance_of(Gitlab::AppTextLogger).to receive(:info).and_call_original
-    expect_any_instance_of(Gitlab::AppJsonLogger).to receive(:info).and_call_original
+      subject.info('Hello World!')
+    end
 
-    subject.info('Hello World!')
+    it 'logs info to AppLogger and AppJsonLogger' do
+      expect_any_instance_of(Gitlab::AppTextLogger).to receive(:info).and_call_original
+      expect_any_instance_of(Gitlab::AppJsonLogger).to receive(:info).and_call_original
+
+      subject.info('Hello World!')
+    end
   end
 
   it 'logs info to only the AppJsonLogger when unstructured logs are disabled' do
-    stub_env('UNSTRUCTURED_RAILS_LOG', 'false')
     expect_any_instance_of(Gitlab::AppTextLogger).not_to receive(:info).and_call_original
     expect_any_instance_of(Gitlab::AppJsonLogger).to receive(:info).and_call_original
 
diff --git a/spec/lib/gitlab/etag_caching/middleware_spec.rb b/spec/lib/gitlab/etag_caching/middleware_spec.rb
index fa0b3d1c6ddfabd75a687b09a8f188cfadc076e5..d25511843ffd9475bdfcebd9a8e3ec45fe8d0849 100644
--- a/spec/lib/gitlab/etag_caching/middleware_spec.rb
+++ b/spec/lib/gitlab/etag_caching/middleware_spec.rb
@@ -145,8 +145,11 @@
       expect(payload[:headers].env['HTTP_IF_NONE_MATCH']).to eq('W/"123"')
     end
 
-    it 'log subscriber processes action' do
-      expect_any_instance_of(ActionController::LogSubscriber).to receive(:process_action)
+    it "publishes process_action.action_controller event to be picked up by lograge's subscriber" do
+      # Lograge unhooks the default Rails subscriber (ActionController::LogSubscriber)
+      # and replaces with its own (Lograge::LogSubscribers::ActionController).
+      # When `lograge.keep_original_rails_log = true`, ActionController::LogSubscriber is kept.
+      expect_any_instance_of(Lograge::LogSubscribers::ActionController).to receive(:process_action)
         .with(instance_of(ActiveSupport::Notifications::Event))
         .and_call_original