The issue with BO is that when markets are volatile, sometimes both target and stop-loss orders get executed instantly. This could result in an additional open position, increasing the risk for both the client and the brokerage firm
We’ve stated the reasons for discontinuing bracket orders here : Why has Zerodha stopped Bracket Orders (BO)?
Alternatively you can use the GTT OCO feature using which you can place both stoploss and target together: How to place a buy GTT One Cancels the Other (OCO) order?
iceberg order feature not available in OCO gtt feature