update_callback is not executing in register_rest_field

I am using below code to get/update custom post meta, get_callback is executing but update_callback is not executing

add_action( 'rest_api_init', 'create_api_posts_meta_field' );
 
function create_api_posts_meta_field() {
 
 // register_rest_field ( 'name-of-post-type', 'name-of-field-to-return', array-of-callbacks-and-schema() )
 register_rest_field( 'experience', 'subtitle', array(
 'get_callback' => 'get_post_meta_for_api',
 'update_callback'   => 'update_post_meta_for_exp',
 'schema' => array(
            'description' => 'Subtitle',
            'type' => 'string',
            'context' => array('view','edit')
        )
    )
 );
}

function update_post_meta_for_exp($value, $object, $field_name ) {
                $havemetafield  = get_post_meta($object['id'], 'experience', false);
                if ($havemetafield) {
                    $ret = update_post_meta($object['id'], 'subtitle', $value );
                    return true;
                } else {
                    $ret = add_post_meta( $object['id'], 'subtitle', $value ,true );
                    return true;
                }
            }

function get_post_meta_for_api( $object ) {
 //get the id of the post object array
 $post_id = $object['id'];
 
 //return the post meta
 return get_post_meta( $post_id )["Subtitle"][0];
}