How to fix 404 Not Found error in Laravel under Ubuntu 20.04?

Question

Apache HTTP Server

I started making an application on Laravel, put it in /var/www/app.test, added a new route to api.php:

<?php

use App\Listing;
use Illuminate\Support\Facades\Route;

Route::get('listing/{listing}', function (Listing $listing) {
    return $listing->toJson();
});

I tried to test this route, but instead of an entry from the table, a 404 Not Found error appears. I thought that this might be related to .htaccess, I changed the apache and site configs as follows:

1) I /etc/apache2/apache.confadded the following lines:

<Directory /var/www/>
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted
</Directory>

2) site config looks like this:

<VirtualHost *:80>
    ServerAdmin [email protected]
    ServerName app.test
    ServerAlias www.app.test
    DocumentRoot /var/www/app.test

    ErrorLog ${APACHE_LOG_DIR}/app_error.log
    CustomLog ${APACHE_LOG_DIR}/app_access.log combined
</VirtualHost>

<Directory /var/www/app.test>
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted
</Directory>

3) the file /etc/apache2/sites-available/000-default.conflooks like this:

<VirtualHost *:80>
    ServerAdmin [email protected]
    DocumentRoot /var/www/html

    <Directory /var/www/html>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>
    
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

mod_rewriteincluded. But after the above changes and restarting apache, the error did not go away. How to fix it?