Sub application routes being picked up in Sveltekit

Describe the bug

I have a sveltekit app that loads sub applications that are pure web components (built in Angular). The Angular WC has it's own routing. The WC loads fine and Angular WC app works fine. However, when it's routes change, it updates the browser URL. This cases a problem on reload of page. The internal sub route from Angular route is not know to the parent Sveletkit app.

How can I prevent these Angular sub routes from updating browser URL. Note: I just moved the parent app from a Svelte app to Sveltekit app recently. Prior to this move, the WC sub routing from Angular app did not surface in browser URL, so it's not an Angular app issue.

Reproduction

An example sveltekit app, with a test Web Component loaded
https://github.com/malindsay/sveltekit-loading-wc/

Logs

No response

System Info

Run sample app to see details

Severity

blocking all usage of svelte

Start by running the reproduction at github.com/malindsay/sveltekit-loading-wc/ and observe how the Angular web component's route changes affect the SvelteKit browser URL. Trace the parent and embedded routing behavior, then verify that internal Angular routes no longer surface in the parent URL and that reloading the page still works.