Paytm is just slowly becoming the trusted website in India. But actually when you mostly shop at it many hackers are just waiting you get indulged in some ads which will appear on the website and when you click on it, the hackers gain that access and are able to see anything you are doing.
My friend has been scanned like this once when the hacker had debited Rs 7000 when he made payment for a Rs 100 recharge. Be aware of it.