Uncaught Error: Call to undefined method ComposerAutoloaderInit Laravel 8.12 - php

Question

I have a Laravel project that should be deployed on Linux machine and served by Nginx.
It runs on PHP 7.4
I cloned project from Git, install vendor packages, and changed .env file for application desired state.
But when I try to access website, I got an error:
Fatal error: Uncaught Error: Call to undefined method
Fatal error: Uncaught Error: Call to undefined method ComposerAutoloaderInit90740c17631bd3f3e829063649c6f6e0::getLoader()
There is my autoload.php content:
<?php
// autoload.php #generated by Composer
if (PHP_VERSION_ID < 50600) {
if (!headers_sent()) {
header('HTTP/1.1 500 Internal Server Error');
}
$err = 'Composer 2.3.0 dropped support for autoloading on PHP <5.6 and you are running '.PHP_VERSION.', please upgrade PHP or use Composer 2.2 LTS via "composer self-update --2.2". Aborting.'.PHP_EOL;
if (!ini_get('display_errors')) {
if (PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg') {
fwrite(STDERR, $err);
} elseif (!headers_sent()) {
echo $err;
}
}
trigger_error(
$err,
E_USER_ERROR
);
}
require_once __DIR__ . '/composer/autoload_real.php';
return ComposerAutoloaderInit90740c17631bd3f3e829063649c6f6e0::getLoader();
I have already tried almost every solution in the internet. But none of them solved my problem.
I just wanna know that it's server-side error or application-side error?