Steps to reproduce the issue

Joomla 5.2.4
Enable Send Copy to Submitter parameter in Contacts component parameters (tab form).
Send a copy to yourself checkbox appears in your contact form
Check this checkbox.

Expected result

Email is sent to the contact and a copy of this email is sent to the user.

Actual result

Email is sent to the contact but the user doesn't receive anything.

Additional comments

This issue is related to PR #37174 as contact.xml has a default="0" for contact_email_copy checkbox.