Specifics of your environment

1. Are you acting as SP/IdP/proxy?
   We're using Okta as an IdP
2. SimpleSAMLphp: What version are you using?
   2.0-beta99, but looking at tags for the commit it seems to be available in 2.1 too
3. PHP: What version are you using?
   8.1
4. Platform: unix or Windows?
   Unix
5. Webserver: Apache/Nginx/ISS?
   Apache

Describe the bug
When upgrading our SimpleSAML installation, it stopped working. We got this error :
Noticed exception 'SimpleSAML\Assert\AssertionFailedException' with message ''Drupal - site.example.com' is not a valid RFC3986 compliant URI' in /var/www/html/vendor/simplesamlphp/assert/src/Assert.php:363

Digging into this, this seems to be linked to this change :
#1658

Expected behavior
EntityID didn't had this restriction before, and audiences in Okta don't have this limitation. Adding this new restriction now seems to be an important breaking change, and would lead to us having to reconfigure many elements. My main issue with this is how other SAML integration don,t have this restriction...

Is this behavior really expected from entityID in SAML? Okta's support page reccomend this, but does not seems to discuss any hard restriction over this : https://support.okta.com/help/s/article/What-Is-the-Audience-URI?language=en_US