Entrusted profit trading has a priority principle, similar to stock futures. Namely: price first, time first, quantity first.

According to this principle, when you entrust the transaction, the price just reaches 8.4. However, A, who also entrusted the transaction at 8.4, was earlier than you, or you and A entrusted 8.4 at the same time, but the amount of A was larger than you, so he gave priority to the transaction.

Also, it's not the first time that a system problem broke out in ICBC, which led to a transaction failure, and so is t+d, so don't be surprised.

That's what happened. I hope I can help you.