You can not use an arbitrary full URL as a `returnUrl`. Instead, use the apps `launchUrl` that you can get from the `currentAppInstallation` query. This is the gist of how I do it (note the link to the GitHub issue that helped me with the same issues...

I am also interested in this for a slightly different use case:From a sub-page of my app I create a subscription based on a certain action. I want the user to be redirected to the page that he was on and not to the home page.

I do have the same issue.Changing the price of a variant does not trigger the product updated webhook. API Version 2021-07. The test event arrives at my desired destination therefore that is not the issue.