Hello Nitesh,
From Istanbul and Jakarta version, If you use a password(encrypted type 2). it will automatically mask the field on service portal. there by you can decrypt that by the following code:
var Encrypter = new GlideEncrypter();
var encrypted = current.variable name;
var decrypted = Encrypter.decrypt(encrypted);
current.u_client_instance_password = decrypted;
current.update();
