Updating ACF via REST API v3

I've added a bunch of custom fields to my WooCommerce site - they turn up fine on the product page and I can have them returned via the API now that I've added the code below - but I can't update them via the API - expect I'm missing something really obvious :)

My code (added using PHP Inster): -

function create_ACF_meta_in_REST() {
    $postypes_to_exclude = ['acf-field-group','acf-field'];
    $extra_postypes_to_include = ["post"];
    $post_types = array_diff(get_post_types(["_builtin" => false], 'names'),$postypes_to_exclude);

    array_push($post_types, $extra_postypes_to_include);

    foreach ($post_types as $post_type) {
        register_rest_field( $post_type, 'ACF', [
            'get_callback'    => 'expose_ACF_fields',
            'update_callback' => 'update_ACF_fields',
            'schema'          => null,
       ]
     );
    }
}

function update_ACF_fields( $data, $object ) {
    $ID = $object['id'];
    return  update_post_meta(  $ID, $data );
}

function expose_ACF_fields( $object ) {
    $ID = $object['id'];
    return get_fields( $ID );
}

add_action( 'rest_api_init', 'create_ACF_meta_in_REST' );

Any pointers would be much appreciated

Fixed it - easy in the end, just an undocumented feature!

For the 'standard' WooCommerce fields, you can just send JSON like this: -

{
"regular_price": "1.25"
}

That works fine and will update the field for the ID that you gave in the endpoint

BUT

For the custom fields, you have to send the following: -

{
"key": "your field name"
"value": "your new value"
}

Doing it this way works fine without any of the additional code that I showed in the question

All good in the end :)