You probably customized that email before we changed the link.
Please go to /admin/customize/email_templates/user_notifications.confirm_new_email and make sure that link in there looks like
%{base_url}/u/confirm-new-email/%{email_token}
instead of
%{base_url}/u/authorize-email/%{email_token}
It might be a good idea to add a migration after all. This came up multiple times already.
cc @sam
https://review.discourse.org/t/feature-improve-email-change-workflow-pr-8377/7150/4