diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 6490826503..36b9b9d87b 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -341,6 +341,10 @@ module ActiveRecord
         ActiveRecord.default_timezone
       end
 
+      def maintain_test_schema # :nodoc:
+        ActiveRecord.maintain_test_schema
+      end
+
       def reading_role # :nodoc:
         ActiveSupport::Deprecation.warn(<<~MSG)
           ActiveRecord::Base.reading_role is deprecated and will be removed in Rails 7.0.
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 279461d892..bf26aaba5f 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -651,7 +651,7 @@ module ActiveRecord
       end
 
       def maintain_test_schema! #:nodoc:
-        if ActiveRecord.maintain_test_schema
+        if ActiveRecord::Base.maintain_test_schema
           suppress_messages { load_schema_if_pending! }
         end
       end
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 8d24fa854d..5622a03bac 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -224,8 +224,15 @@ To keep using the current cache store, you can turn off cache versioning entirel
         configs.each do |k, v|
           next if k == :encryption
           setter = "#{k}="
-          next if ActiveRecord.respond_to?(setter)
-          send(setter, v)
+          # Some existing initializers might rely on Active Record configuration
+          # being copied from the config object to their actual destination when
+          # `ActiveRecord::Base` is loaded.
+          # So to preserve backward compatibility we copy the config a second time.
+          if ActiveRecord.respond_to?(setter)
+            ActiveRecord.send(setter, v)
+          else
+            send(setter, v)
+          end
         end
       end
     end