As per Zerodha, it is due to the broadcast ticks not capturing/reflected in our system.
Try to capture BANKNIFTY FUTURES FOR THE WHOLE DAY. Then save the chart as image. then open the same again in Pi. And compare.
I have done this exercise and there is lot of difference between the chart formed at our system and the chart formed at Zerodha server. Some time I have noticed that the ticks at my system is not reflected in Zerodha server.
So which one is correct?