How do I document union type variables?

My module has a class with a union type member variable

/**
 * This is a PHPv8 union type variable that can be a string OR null.
 *
 * @var string|null
 */
protected string|null $myVar;

However, when I run the code sniffer with phpcs --standard=Drupal,DrupalPractice ..., I'm always getting an error like

FILE: MyDummyClass.php
----------------------
FOUND 1 ERROR
----------------------
  46 | ERROR   | Missing member variable doc comment
----------------------

In this special case, I was able to use the nullable shorthand as a workaround

/**
 * This is a PHPv8 union type variable that can be a string OR null.
 *
 * @var string
 */
protected ?string $myVar;

But this workaround only works for one single nullable union. As soon as I use the union operator | in the @var line

/**
 * This is a PHPv8 union type variable that can be a string OR int OR null.
 *
 * @var string|int
 */
protected ?string|int $myVar;

I'm getting the phpcs error message again.

So how do I properly document union type variables, following Drupal practices?