WordPress – Form does not filter the results of taxonomies

Try below code for search using date and category.

$_name = $_GET['date-picker-example'];
$categoria = $_GET['categoria_evento'];
$today = date('Ymd');
// Start the Query
$v_args = array(
    'post_type'     =>  array('eventi-suite'), // your CPT
    'posts_per_page'    => -1,
    'meta_value'    =>  $_name, // looks into everything with the keyword from your 'name field'
    'order'      => 'ASC',
    'orderby' => 'metakey_AMC_data',
    'meta_query' => array(
        array
        (
            'key'     => 'metakey_AMC_data',
            'compare'   => '>=',
            'value'     => $today,

        ),
    ),
    'tax_query' => array(
        array(
          'taxonomy' => 'categoria',
          'field' => 'slug',
          'terms' => $categoria
        )
    );

));
$vehicleSearchQuery = new WP_Query( $v_args );