Add custom taxonomies to the WP-API

wp-api-custom-taxonomies.php

<?php

function ms_add_tax_to_api() {
    $taxonomies = get_taxonomies( '', 'objects' );
    
    foreach( $taxonomies as $taxonomy ) {
	    $taxonomy->show_in_rest = true;
    }
}
add_action( 'init', 'ms_add_tax_to_api', 30 );