{confirmation_link.URL} redirects but does not confirm the contact

[Brennitschka]

Groundhogg version: Version 4.5.15
WordPress version: WordPress 7.0.4

Problem

Using the documented syntax {confirmation_link.https://example.com/page/}
the contact is redirected to the target page, but the opt-in status is
NOT changed to Confirmed. The contact stays Unconfirmed.

Using the plain {confirmation_link} works correctly — the contact is
confirmed as expected.

Steps to reproduce

1. Create a flow: web form -> send double opt-in email -> until opt-in
   status is confirmed
2. In the email, use {confirmation_link.https://example.com/page/}
3. Submit the form with a new email address (logged out, private window)
4. Click the confirmation link in the email
5. The target page loads, but the contact record still shows Unconfirmed

Expected

The contact should be confirmed and then redirected to the target page.

Notes

The syntax is documented here:
https://help.groundhogg.io/article/441-how-do-i-redirect-a-contact-after-they-have-confirmed-their-email

The article is from November 2020. Since then the tracking link structure
has changed and links were hardened against redirect attacks. Possibly
the argument is no longer supported and the documentation is outdated.