Steps to reproduce

1. Use the unified search and write a unique term that matches just one email subject

Expected behavior

Search only lists emails with matching subject.

Actual behavior

Search lists all emails (no filter applied)

Mail app version

main

Additional info

Was introduced here: https://github.com/nextcloud/mail/pull/8897/files#diff-39657503b9cdd0f0fa8292196e6432d8a918b4d16ab8212f2a5c9b6f67857e86

Term must be parsed as subject:term.