How does there is an increase in Open Interest of yesbank even when it is under F&O Ban
Normally it should not happen but if any client/broker violates it they will be charged heavily. Small brokers may not keep ban limit, or few may allow intraday and due to some reasons position may not be closed.
Market wide Position Limit violation
At the end of each day during which the ban on fresh positions is in force for any security, when any member or client has increased his existing positions or has created a new position in that security the client/trading members will be subject to a penalty 1% of the value of increased position subject to a minimum of Rs.5000 and maximum of Rs.100000. The positions, for this purpose, will be valued at the underlying close price.
Full penalty sheet here.