Canonical URL placeholder shows wrong URL on subdirectory install

[loilo]

Describe the bug
The SEO Framework outputs

How to reproduce the bug

Conveniently, we can use the WordPress Playground to demo the issue as every playground runs in a subdirectory.

1. Go to https://playground.wordpress.net/?plugin=autodescription
2. Go to Pages → Sample Page and click "Edit" (or paste /wp-admin/post.php?post=2&action=edit into the virtual browser)
3. Activate the "Visibility" tab of the SEO settings and notice how the placeholder deviates from what the actual URL is
   when opening the page or clicking on the "Link" in the sidebar (see screenshot below).

Expected behavior
The actual canonical URL should be shown as the placeholder.

Screenshots

Additional context
It's worth noting that the server-side filling of the placeholder actually puts in the correct URL (not really demonstratable in the playground). It's the JavaScript code (tsfCanonical.updateStateOf) running after that which leads to the incorrect value.