Why do Huawei's SMS messages automatically delete?

In one case, the automatic message cleaning function is turned on and can be turned off in the message setting center. The steps are as follows:

Open Huawei's own SMS app；;

Click Menu-Settings;

Uncheck Delete to delete the information.

In another case, a third-party housekeeping and security application is installed in the mobile phone, and under certain conditions, the SMS will be automatically deleted and such housekeeping and security applications will be uninstalled.