Email address suggestions ignore system “Accounts” contacts, only personal contacts are suggested

Steps to reproduce

1. Log in as a user that has access to system address book Accounts (e.g. via LDAP / system address book).
2. Ensure that the Accounts address book is visible in the Contacts app and contains contacts with email addresses.
3. Open the Mail app and click New message.
4. In the To: field, start typing the name or email of a contact that exists only in the Accounts/system contacts (not in Personal).
5. Observe the autocomplete suggestions.

Expected behavior

Contacts from the system Accounts address book should appear in the autocomplete suggestions when composing an email, just like contacts from the Personal address book.

Actual behavior

Only contacts from the Personal address book appear in the suggestions.
Contacts from the Accounts / system contacts address book are not suggested at all.

Mail app version

5.6.5

Nextcloud version

32.0.2

Mailserver or service

No response

Operating system

No response

PHP engine version

None

Nextcloud memory caching

No response

Web server

None

Database

None

Additional info

• The contacts in the Accounts address book are visible and searchable in the Contacts app itself.
• Autocomplete suggestions in the Mail app work correctly for contacts stored in Personal.

contacts app version 8.1.2