From https://typesense.org/docs/28.0/api/#what-s-new:
Support validate_field_names parameter to disable field name validation in faceting, filtering and grouping operations.
However, this field is not present anywhere in https://github.com/typesense/typesense-api-spec/blob/09eefc06ef45edd777b63f16d3714a8ae85d12db/openapi.yml