@Mio2fresh,
From the Kasa app, there is no real way to tell if a device was disconnected for a time. You would most likely have more success finding this in your router settings. If it was recent you may be able to find some sort of uptime that would indicate how long a device has been connected. How are you recording the footage on these devices? Are these cloud recordings, or are they recording to an SD Card?
I have not seen any reports of a cloud failure in the last few weeks, I think the last outage was over a month ago and affected only a small region of the Pacific Islands.
If you do believe that it was a disconnect, you may try to set an IP reservation for the device, which would give a guaranteed route for its connection.