以下逻辑可能会有所帮助:

<?php
class MyClass
{
    public $id = null;

    public function setId($id) {
        $this->id = $id;
        return $this;
    }
}

$arr1 = [
    (new MyClass())->setId(1),
    (new MyClass())->setId(2),
    (new MyClass())->setId(3),
];

$arr2 = [
    (new MyClass())->setId(1),
    (new MyClass())->setId(2),
];

$difference = array_udiff($arr1, $arr2,
    function ($objOne, $objTwo) {
        return $objOne->id - $objTwo->id;
    }
);

输出:

Array
(
    [2] => MyClass Object
        (
            [id] => 3
        )

)

工作演示