Why can you call a private method on a new instance made inside a public method of the same class type, in PHP?

Why can you call a private method on a new instance made inside a public method of the same class type?

class Foo
{
    private function thePrivateMethod()
    {
        echo 'can not be called publicly?';
    }

    public function thePublicMethod()
    {
        $clone = new Foo;
        $clone->thePrivateMethod();
    }
}

$foo = new Foo();
$foo->thePublicMethod();
$foo->thePrivateMethod();

The above results in the following output when run in PHP 7.3.18

can not be called publicly?

Fatal error:  Uncaught Error: Call to private method Foo::thePrivateMethod() from context

Intuitively, I would expect the first call to Foo::thePrivateMethod() to also cause a fatal error. But I’m not able to find in the documentation that this behaviour would be allowed?