Based on the issue description and the hints provided, I can create the patch. The issue clearly states:

1. The problem is in `django.contrib.admin.helpers` in the `get_admin_url` function
2. The line `url = reverse(url_name, args=[quote(remote_obj.pk)])` needs to be changed to include `current_app=self.model_admin.admin_site.name`
3. This was confirmed as the correct fix in the discussion

Here's the patch:

--- a/django/contrib/admin/helpers.py
+++ b/django/contrib/admin/helpers.py
@@ -209,7 +209,11 @@ class AdminReadonlyField:
                 remote_obj.pk,
             )
             try:
-                url = reverse(url_name, args=[quote(remote_obj.pk)])
+                url = reverse(
+                    url_name,
+                    args=[quote(remote_obj.pk)],
+                    current_app=self.model_admin.admin_site.name,
+                )
                 return format_html('<a href="{}">{}</a>', url, remote_obj)
             except NoReverseMatch:
                 return str(remote_obj)