Changes

config/install/services_api_key_auth.settings.yml

 server_api_key_name: 'api_key'
 post_api_key_name: ''
-get_api_key_name: 'api_key'
+get_api_key_name: ''

services_api_key_auth.install

@@ -10,7 +10,8 @@ declare(strict_types=1);
 /**
  * Introduces new settings.
  *
- * Makes the request api key names configurable.
+ * Makes the request api key names configurable. And set their defaults to the
+ * old programmatically set values.
  */
 function services_api_key_auth_update_10001() {
   \Drupal::configFactory()->getEditable('services_api_key_auth.settings')

services_api_key_auth.links.menu.yml

@@ -10,5 +10,5 @@ services_api_key_auth.api_key_auth_settings:
   title: Request API Key Authentication settings
   description: The request api key authentication settings
   parent: system.admin_config_system
-  route_name: services_api_key_auth.api_key_auth_settings
+  route_name: system.admin_config_services
   weight: 10

services_api_key_auth.routing.yml

@@ -34,7 +34,7 @@ entity.api_key.delete_form:
         with_config_overrides: TRUE
 
 services_api_key_auth.api_key_auth_settings:
-  path: '/admin/config/system/api-key-auth-settings'
+  path: '/admin/config/services/api-key-auth-settings'
   defaults:
     _title: 'Request API Key Authentication settings'
     _form: 'Drupal\services_api_key_auth\Form\ApiKeyAuthSettingsForm'

tests/src/Functional/ApiKeyFormElementTest.php → tests/src/Functional/ApiKeyFormTest.php

@@ -9,7 +9,7 @@ use Drupal\Tests\BrowserTestBase;
  *
  * @group services_api_key_auth
  */
-class ApiKeyFormElementTest extends BrowserTestBase {
+class ApiKeyFormTest extends BrowserTestBase {
 
   /**
    * {@inheritdoc}
@@ -35,6 +35,8 @@ class ApiKeyFormElementTest extends BrowserTestBase {
 
   /**
    * Tests if the module installation, won't break the site.
+   *
+   * @see https://www.drupal.org/project/services_api_key_auth/issues/2928649
    */
   public function testApiKeyFormElementCausingAccessDenied() {
     // Set the post_api_key_name to "api_key":