Siteimprove code configured through settings.php not displaying in UI

When adding the siteimprove code to settings.php file, it will just display an empty field in the configuration UI (/admin/config/system/siteimprove-analytics).

Using the following code to get the settings seems to fix it:

$config = \Drupal::config('siteimprove_analytics.settings');
# Before:
# $config = $this->config('siteimprove_analytics.settings');