I tried an update from aaPanel 6.8.27 to 6.8.28 leading to 8 security alerts. Among them, one talked about a better SSH timeout in the range [300,900] seconds. So, I modified it to 900 in sshd_config and the alert persisted. Putting 899 worked. So, the check in your current code is certainly [300, 900[; just a "<" to change to "<=" 🙂