You didn't attach the screenshot to the original message, otherwise I could definitely see it as an admin 🙂
The "Deauthorize" message is coming from Endpoint Security on Demand (ESOD), which is related to Mobile Access.
It generally means someone is trying to log into the gateway and is failing the ESOD check.
If you're not seeing other traffic logs, perhaps a cprestart (requires an outage) will restore normal logs?
Otherwise, since you're on a long unsupported version, I recommend upgrading to a supported release.