Current theme name is not correct in case of multi-domain site

Hi,

I am working with the multidomain site and each domain have a different theme. I have noticed on my running site that one method "getFilePathByKey" in CriticalCssService.php is not giving the correct active theme name. It is always giving default set theme name which is wrong in my site. I'm on the latest version of D8.

I thought the issue is related to $themeName = $this->configFactory->get('system.theme')->get('default'); which should be replaced with $themeName = \Drupal::service('theme.manager')->getActiveTheme()->getName();