Hi WPMUDEV Heroes.
It is not User Activity but Quick Status but we could not find it in that long list which is still not a-z sorted!!! - since 3 months meanwhile nothing changed the chaos of that dropdown list ! please change it to A-Z. Thanks
Anyways we have Anti Malware fro GOTMLS.NET installed and we get only one serious thread message. Wordpress plugin: gotmls
see screenshots about the WPMUDEV quick-status plugin!
I would suggest that you check your plugin and release an update where this message does not appear and everything would be OK.
Of course all WPMUDEV stuff got downloaded from the WPMUDEV site!