For those newly facing the same problem:

Open the file: `vendor/tecnickcom/tcpdf/config/tcpdf_config.php`

After changing the constant K_TCPDF_CALLS_IN_HTML value to true

You still need to allow the method for using define('K_ALLOWED_TCPDF_TAGS', '|write2DBarcode|');

Check the following reply for understanding this constant:

Missing documentation on K_ALLOWED_TCPDF_TAGS