Virtual fields set by BeforeReadCollectionHook return data unflattened (always in all locales)

I have a [virtual](

) path, breadcrumbs and alternatePaths field on my collection items.

Since now, I used field afterRead hooks to generate the breadcrumbs based on the items parent page and the path and alternatePaths based on the breadcrumbs. This worked fine.

To improve the performance (only recursively iterate over the parents once instead of for each of the hook), I now want to use a BeforeReadCollection hook to get the data for the virtual fields. I do this as follows:

const setVirtualFieldsHook: CollectionBeforeReadHook = async ({ doc, req, collection }) => {
    const breadcrumbs = await getBreadcrumbsForAllLocales({
      req,
      collection,
      parentField,
      parentCollection,
      data: doc,
    })

    const paths = {
      de: pathFromBreadcrumbs({ locale: 'de', breadcrumbs: breadcrumbs.de }),
      en: pathFromBreadcrumbs({ locale: 'en', breadcrumbs: breadcrumbs.en }),
    }

    const alternatePaths = {
      de: paths.de,
      en: paths.en,
    }

    if (req.locale === 'all') {
      return {
        ...doc,
        path: paths,
        breadcrumbs,
        meta: {
          ...doc.meta,
          alternatePaths,
        },
      }
    } else {
      return {
        ...doc,
        path: paths[req.locale as 'de' | 'en'],
        breadcrumbs: breadcrumbs[req.locale as 'de' | 'en'],
        meta: {
          ...doc.meta,
          alternatePaths,
        },
      }
    }
  }

export const Pages: CollectionConfig = {
   ....
   hooks: {
           beforeRead: [setVirtualFieldsHook],
    },
   fields: [
      path: { type: text, ... },
      breadcrumbs: { type: 'array', ...}
      meta: { type: group, ..., fields: { name: 'alternatePaths', type: 'array', ... }},
    ]
    ....
}

The issue I have, is that the localized path and breadcrumb fields are not flattened.

(My comment below contains an example result from the REST API)

For example, this query:

Returns the following unflattened data:

{
  ...
  "breadcrumbs": {
    "de": [
      {
        "slug": "galerie",
        "path": "/de/galerie",
        "label": "Galerie"
      },
      {
        "slug": "glamping-galerie",
        "path": "/de/galerie/glamping-galerie",
        "label": "Glamping Galerie"
      }
      ],
    "en": [
      {
        "slug": "gallery",
        "path": "/en/gallery",
        "label": "Gallery"
      },
      {
        "slug": "glamping-gallery",
        "path": "/en/gallery/glamping-gallery",
        "label": "Glamping Gallery"
      }
    ]
  },
}

I added a logging statement to the end of the hook, and the hook respects the locale and returns the data correctly. I guess the problem is somewhere else.

Am I doing something wrong, or is this an issue with Payload?

Virtual fields set by BeforeReadCollectionHook return data unflattened (always in all locales)