Filtro para remover tax_query duplicadas da $query do WordPress

tax_query_cleanup.php

<?php

// Filtro para remover tax_query duplicadas da $query do WordPress

function tax_query_cleanup( $query ) {
    if ( is_admin() || ! $query->is_main_query() ) {
        return;
    }

    $tax_query = $query->get( 'tax_query' );

    if ( ! empty( $tax_query ) ) {
        $unique_tax_query = [];
        $seen = [];

        foreach ( $tax_query as $key => $condition ) {
            if ( ! is_array( $condition ) || ! isset( $condition['taxonomy'], $condition['terms'] ) ) {
                continue;
            }

            $identifier = $condition['taxonomy'] . '-' . ( is_array( $condition['terms'] ) ? implode( ',', $condition['terms'] ) : $condition['terms'] );

            if ( ! in_array( $identifier, $seen ) ) {
                $unique_tax_query[] = $condition;
                $seen[] = $identifier;
            }
        }

        // Se limpamos algo, redefinimos a query
        if ( count( $unique_tax_query ) !== count( $tax_query ) ) {
             $query->set( 'tax_query', $unique_tax_query );
        }
    }
}
add_action( 'pre_get_posts', 'tax_query_cleanup', 9999 );