Rendering component in php class breaks parent component in livewire 3

In livewire 2 I used to sometimes mount Component in PHP Class and pass it as variable to blade. Please check following:

	public function render()
	{
    	$this->var = Livewire::mount('system.component')->html();

    	return view('livewire.system.item');
	}

Blade:

{{ $var }}

There are some reasons for this. Eg. I pass this var to modal.

Now in Livewire 3 Im trying to do the same, but cant get it working.

First thing is we lost ->html() method. So I`m just trying to run

$this->var = Livewire::mount('system.component');

And the main thing layouts.app blade stops receiving anything in @stack('scripts').

Any ideas how can I mount the Component in PHP Class? I want to pass it as rendered HTML string to blade.