prop_get_test2.php

<?php

class A
{
    private $a;

    public function __construct($a)
    {
        $this->a = $a;
    }
}

class B extends A
{
    private $a; // extend A in order to force XDebug to use *A*a for `a` property of `A`

    public function __construct($a, $pubA)
    {
        parent::__construct($a);
        $this->a = $pubA;
    }
}

$collision = new B([[[123]]], "whatever");
$collision->{"*A*a"} = 789;

$q = [[[$collision]]];

xdebug_break();
// now you won't be able to get the array `[[[123]]]` which lies by the
// path `$q[0][0][0]->*A*a` (where *A*a means field `a` in the scope of `A`)
// Instead, XDebug will always be returning `789` in the response rendering the value above unreachable