Wrap additional routes by dash(-). And remove those routes from path_regex.rb.

config/routes/group.rb

@@ -24,11 +24,13 @@ scope(path: 'groups/*group_id',
     post :toggle_subscription, on: :member
   end
 
+  scope path: '-' do
     namespace :settings do
       resource :ci_cd, only: [:show], controller: 'ci_cd'
     end
 
     resources :variables, only: [:index, :show, :update, :create, :destroy]
+  end
 end
 
 scope(path: 'groups/*id',

lib/gitlab/path_regex.rb

@@ -129,8 +129,6 @@ module Gitlab
       pipeline_quota
       projects
       subgroups
-      settings
-      variables
     ].freeze
 
     ILLEGAL_PROJECT_PATH_WORDS = PROJECT_WILDCARD_ROUTES