Source

File: wp-admin/includes/class-wp-terms-list-table.php

public function current_action() {
		if ( isset( $_REQUEST['action'] ) && isset( $_REQUEST['delete_tags'] ) && ( 'delete' === $_REQUEST['action'] || 'delete' === $_REQUEST['action2'] ) ) {
			return 'bulk-delete';
		}

		return parent::current_action();
	}