When updating a Guide's targeting to a completely different URL, you should also update the Redirect URL field if the Redirection option is turned on. Otherwise, when you trigger the Guide, the old targeting's URL will be recalled, and you're going to be redirected there.
Not changing the redirection means that you carried a guide but left its first step behind. And old redirection will always override the guide migration and redirect you to its old targeting.
You can change the URL from the Panel or the Chrome Extension.
To update it on the Extension, click on the Guide's name > Settings > Redirect tab.
To update it through the Panel, navigate to the Guides section and click on the settings of the desired Guide.
Then you can find the Redirection section and its URL field at the bottom of the page.
If you would like to learn more about this topic, you can check this article.