This is because the other party has set message and comment permissions.

The setting steps are as follows:

1. Log in to your QQ and click the QQ space icon as shown in the picture.

2. Then click under the settings icon Permission settings.

3. Then click on Message Comments and Anti-harassment under permission settings.

4. Select Only yourself as shown in the picture, and the settings will take effect after saving.

5. In this way, others will not be able to comment on what you say and leave messages in your own space.