Wait... I just found out a less secure but faster way to get money back to China.

With Wise and Alipay, I can send money to Wise from OCBC, then covert it to CNY, when send it to Alipay and then send it to my bank.

Apparently it's not from bank to bank so if someone (like wise or alipay) decide to suspend my transfer, it will be a hard time to get my money back.

But I did a quick test: Send 25 CNY buy only got 9, wise take 16 CNY as a fee. It only takes less than 10 minutes!