Collection's @id is wrong when summarized as a child

How to replicate:

• Go to https://volto.kitconcept.com/
• Create a folder, add a collection inside
• In the folder, as part of that folder's listing, the collection URL is wrong, it's the same as the folder's.

The issue seems to be related to this code: https://github.com/plone/plone.restapi/blob/master/src/plone/restapi/serializer/collection.py#L21

        batch = HypermediaBatch(self.request, results)

        results = collection_metadata
        if not self.request.form.get("fullobjects"):
            results["@id"] = batch.canonical_url

The HypermediaBatch batch object uses the wrong "root".

Start in src/plone/restapi/serializer/collection.py around the HypermediaBatch construction and compare its canonical URL when a collection is listed as a child. Reproduce the folder-and-collection scenario from the issue, then verify that the child collection's summarized @id is its own URL rather than the parent folder's URL.