Are you asking what is the reason for the red exclamation mark in QQ Music private messages? The other party is added to the blacklist, network problems, etc.

The other party is added to the blacklist: If the other party adds you to the blacklist, the message sent will be displayed as an exclamation mark. Just add the other party again.

Network problem: If the other party's network connection is poor and the message cannot be received, an exclamation mark will be displayed. Just reconnect to the network at this time.