The redirection issue occurs while using the Admin Tools plugin for Joomla SAML SSO, where the Admin Tools plugin makes changes in the .htaccess file and adds certain rules that prevent redirection from the site.
You can solve the above issue by following the steps given below:
1. Navigate to Admin tools >> Control Panel then click on the .htaccess maker option.
2. Then disable the option ‘Protect against common file injection attacks’.
3. Then clear the cache for your site and test for Single Sign-On.