On testing a new event form, we have discovered, by accident, that we can complete the registration form without a valid email address. The email address is required, so the field has to have something in it, but it doesn't have to be a valid email address. Same for the phone number field, although it's not require, it doesn't have to be a phone number.
This form: https://birthmark.org/pan is using the "New Individual" reserved profile for the name, email, and phone. This same form, without the WP shortcode is here https://birthmark.org/civicrm/event/register/?reset=1&id=29, but the behavior is the same (to rule out a shortcode error).
Error logs for the site do not show any errors related to this. Civi error logs also don't have any errors. Console shows a few warnings, but they are related to fonts and image preloading.
This is not happening in contribution pages, only event registrations.
I'm not sure what my next troubleshooting step should be, without any errors to guide me. Any help or ideas would be greatly appreciated.
I have disabled all the extensions that I possibly can to rule those out. I have disabled all custom templates.
WordPress 6.6.2 CiviCRM 5.78.3