https://musicbrainz.org/ws/2/artist/b10bbbfc-cf9e-42e0-be17-e2c3e1d2600d?inc=tags contains entries like

<tag-list>
  <tag count="-2">
    <name>heavy metal</name>
  </tag>
</tag-list>

which violate our XML schema: https://github.com/metabrainz/mmd-schema/blob/b8d2faf/schema/musicbrainz_mmd-2.0.rng#L1452-L1454

Rather than changing the XML schema, I suggest removing tags with negative vote counts from the output, similar to how we recently removed user-downvoted tags in MBS-12155. I can't think of any real use case for these that isn't academic (and you'd probably want a database dump for that).

This wouldn't affect Picard's "only use my genres" feature, because those by definition come from the user-tags list.