conf.d/70-no-bitmaps-except-emoji.conf

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
<fontconfig>
  <description>Reject bitmap fonts except bitmap emoji fonts</description>
  <!-- Reject bitmap fonts -->
  <selectfont>
    <rejectfont>
      <pattern>
        <patelt name="outline"><bool>false</bool></patelt>
        <patelt name="scalable"><bool>false</bool></patelt>
      </pattern>
    </rejectfont>
  </selectfont>
</fontconfig>