Title: Infinite loading (hang) after submitting credentials on Apache/FastCGI

Issue summary: After installing and enabling the Shield module on a Drupal 10 site hosted on an Apache server, the authentication process fails.

Steps to reproduce:

Install Shield module.
Set a simple user/password.
Enter the credentials when the browser prompt appears.

Results: The browser starts loading indefinitely (spinning icon). The page never renders, and the server does not complete the request.

Expected results: The site should load immediately after successful authentication.

Additional information:
The issue persists even with "Allow command line access" enabled.
Uninstalling the module via Drush immediately restores site accessibility.