laravel sanctum for API authentication and laravel build in authentication for web

I am new to do laravel and Vue js web application. in my laravel project already works with laravel default authentication. When I use Vue js for frontend, I used laravel sanctum for api authentication. This is working for Vue js frontend but my default laravel authentication for backend admin login is not working when I add
SESSION_DOMAIN=localhost
SANCTUM_STATEFUL_DOMAINS=localhost in .env file.
When I removed those two lines, sanctum is not working but default authentication was working again. how to fix that problem. I want to work with my laravel backend admin panel login with laravel default authentication and want to work with laravel sanctum for vue js frontend user login. Could you please help me? Thanks.

.env

SESSION_DOMAIN=localhost
SANCTUM_STATEFUL_DOMAINS=localhost

I used the same domain for backend and frontend. For example,

For admin login

http://127.0.0.1:8000/admin/login

For frontend login

http://127.0.0.1:8000/login

in web.php

Route::namespace('Admin')->prefix('admin')->group(function() {

     Route::namespace('Auth')->group(function() {

        // Authentication Routes
        Route::get('/login', 'LoginController@showLoginForm')->name('admin.login');
        Route::post('/login', 'LoginController@login');

        Route::post('logout', 'LoginController@logout')->name('admin.logout');

    });

});

in api.php

Route::post('/login', 'Auth\LoginController@userLogin');

admin login

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when login, it shows the error after adding SESSION_DOMAIN=localhost, SANCTUM_STATEFUL_DOMAINS=localhost in .env

enter image description here