How to debug mail event error upon Laravel Upgrade?

I am using Laravel 11 which has been upgraded from Laravel 10 with Laravel Breeze.

When executing the event: event(new Registered($user)); two email verification mails are sent when User model implements MustVerifyEmail upon user registration.

Any ideas how to debug this further? The project is currently stuck at laravel/framework v11.8.0.

I can see that this file vendor/laravel/framework/src/Illuminate/Foundation/Console/stubs/view-mail.stub is only in version 11.9.0 and not 11.8.0. Same issue present in version 11.21.

My steps to reproduce the error:

composer require laravel/framework:11.8.0; php artisan test --filter=UserRegistrationTest
composer require laravel/framework:11.9.0; php artisan test --filter=UserRegistrationTest

Postgres 16.3 PHP 8.3.6

composer.json require:

"require": {
        "php": "^8.2",
        "awcodes/filament-table-repeater": "^3.0",
        "bezhansalleh/filament-shield": "^3.2",
        "brunocfalcao/blade-feather-icons": "^4.0",
        "cheesegrits/filament-google-maps": "*",
        "codebar-ag/laravel-bexio": "^1.1",
        "filament/filament": "*",
        "filament/spatie-laravel-media-library-plugin": "^3.2",
        "filament/spatie-laravel-settings-plugin": "^3.2",
        "flowframe/laravel-trend": "^0.2.0",
        "guava/filament-icon-picker": "^2.0",
        "guzzlehttp/guzzle": "^7.2",
        "inertiajs/inertia-laravel": "^1.0",
        "intervention/image-laravel": "^1.0",
        "laravel/framework": "^11.21",
        "laravel/horizon": "^5.23",
        "laravel/sanctum": "^4.0",
        "laravel/tinker": "^2.8",
        "livewire/livewire": "^3.3",
        "malzariey/filament-daterangepicker-filter": "^2.7",
        "postare/blade-mdi": "^1.0",
        "pusher/pusher-php-server": "^7.2",
        "ryangjchandler/blade-tabler-icons": "^2.3",
        "ryangjchandler/laravel-cloudflare-turnstile": "^1.1",
        "spatie/laravel-pdf": "^1.5",
        "spatie/laravel-permission": "^6.3",
        "tightenco/ziggy": "^2.0",
        "ysfkaya/filament-phone-input": "^2.2"
    },

Thank you.