Deprecated: Creation of dynamic property db::$required is deprecated [duplicate]

Deprecated: Creation of dynamic property db::$required is deprecated in /home1/include/connection.php on line 24

Fatal error: Uncaught Error: Object of class mysqli could not be converted to string in /home1/include/connection.php:27 Stack trace: #0 /home1/include/connection.php(471): db->__construct() #1 /home1/include/index.php(1): include(‘/home1/…’) #2 {main} thrown in /home1/include/connection.php on line 27

My Code:

class db
{
    var $iConn;
    private $dbHost;
    private $dbUser;
    private $dbPass;
    private $dbName;

    public function __construct(){
        $this->dbHost = "localhost";
        $this->dbUser = "thewcmp_automation";
        $this->dbPass = "6K_l+W)74Sv5";
        $this->dbName = "thewcmp_dashboard";
            
        $iConn = $this->required = mysqli_connect($this->dbHost, $this->dbUser, $this->dbPass, $this->dbName);

        //check connection
        if (mysqli_connect_errno($this->$iConn))
        {
            echo "Failed to connect to MySQL:" . mysqli_connect_error();
        }
    }
}

Is this bcoz of PHP version? or any help please.

Can any one guide me or correct the Code for me please. Thanks in advance