The filter can be used if it’s needed to change the subject while sending the subscription confirmation email.
Changelog
Since 7.6.1 version
Parameters
1. $subject – the subject of the subscription confirmation email
2. $postId – the ID of the current post
3. $email – the email where the confirmation email is sent
Usage
add_filter('wpdiscuz_confirm_email_subject', function($subject, $postId, $email){
return 'My Custom Subject';
}, 10, 3);