Mail: include URL from which form was sent

Hi, we have set all forms to include the URL of the page from which the form was filled. This way we know which post/portfolio page the customer is interested in. Under the Mail tab, we use for posts:
[_post_title]
[_post_url]

or

This shortcode for pages:
[_URL]

Now, this last one today did not include the home page URL (https://www.studiogest.ch/en) but something like https://www.studiogest.ch/wp-json/contact-form-7/v1/contact-forms/1994/feedback

We use Autoptimize, btw. What’s wrong?

Thanks in advance.
M

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