why was the environment variable `DB_PORT` replaced with another value?

dotenv

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=4000
DB_DATABASE=test
DB_USERNAME=root
DB_PASSWORD=

config/databases.php


        'mysql' => [
            'driver' => 'mysql',
            'host' => env('DB_HOST', '127.0.0.1'),
            'port' => env('DB_PORT', '3306'),
            'database' => env('DB_DATABASE', 'forge'),
            'username' => env('DB_USERNAME', 'forge'),
            'password' => env('DB_PASSWORD', ''),
            'unix_socket' => env('DB_SOCKET', ''),
            'charset' => 'utf8mb4',
            'collation' => 'utf8mb4_unicode_ci',
            'prefix' => '',
            'strict' => true,
            'engine' => null,
            'modes'  => [
                'ONLY_FULL_GROUP_BY',
                'STRICT_TRANS_TABLES',
                'NO_ZERO_IN_DATE',
                'NO_ZERO_DATE',
                'ERROR_FOR_DIVISION_BY_ZERO',
                'NO_ENGINE_SUBSTITUTION',
            ],
        ],

but var_dump :

    ["mysql"]=>
    array(13) {
      ["driver"]=>
      string(5) "mysql"
      ["host"]=>
      string(9) "127.0.0.1"
      ["port"]=>
      string(21) "tcp://10.0.9.193:4000"    // replaced ??!!??
      ["database"]=>
      string(4) "test"
      ["username"]=>
      string(4) "root"
      ["password"]=>
      string(0) ""
      ["unix_socket"]=>
      string(0) ""
      ["charset"]=>
      string(7) "utf8mb4"
      ["collation"]=>
      string(18) "utf8mb4_unicode_ci"
      ["prefix"]=>
      string(0) ""
      ["strict"]=>
      bool(true)
      ["engine"]=>
      NULL
      ["modes"]=>
      array(6) {
        [0]=>
        string(18) "ONLY_FULL_GROUP_BY"
        [1]=>
        string(19) "STRICT_TRANS_TABLES"
        [2]=>
        string(15) "NO_ZERO_IN_DATE"
        [3]=>
        string(12) "NO_ZERO_DATE"
        [4]=>
        string(26) "ERROR_FOR_DIVISION_BY_ZERO"
        [5]=>
        string(22) "NO_ENGINE_SUBSTITUTION"
      }
    }

ti-click / laravel-realworld-example-app

why was the environment variable `DB_PORT` replaced with another value? #1