Partial mocking a Facade ignores the variables that are set in the constructor

I have a class names AbcService

<?php

namespace AppHttp;

class AbcService
{

    private string $attr;

    public function __construct()
    {
        $this->attr = 'some text';
    }

    public function aMethod(): bool
    {
        if (empty($this->attr)) {
            return true;
        }

        return false;
    }

    public function bMethod()
    {
        return 'what';
    }

}

I’ve created a facade on top of that:

<?php

namespace AppHttp;

use IlluminateSupportFacadesFacade;

class Abc extends Facade
{
    protected static function getFacadeAccessor()
    {
        return AbcService::class;
    }
}

Now calling this code from the tink session (php artisan tink) outputs true, meaning that the attr value did not change in the constructor.

use AppHttpAbc;
Abc::partialMock();
Abc::shouldReceive('bMethod')->once()->andReturn('partialMock');
print_r(Abc::aMethod());

I’ve placed a dd in the constructor after changing the value of attr and we know after calling the Abc::partialMock() the constructor executed. Is this the normal behavior of the partialMock in the Facade? How can I only mock the bMethod method and use other part of the class without changes?