Cam captures phantom...dust particles(?) and now nothing

One of my cams have been capturing…who knows what. Green box changing shape, size and moving around at random, with no human anywhere near. Since this ‘upgrade’, the playback of the sd card indicates extended capture - green vertical lines, but “no video at the selected time”. This is alarming, as I really need to see if anyone was present - no one should be.

Turn on the detection zone.
This is your answer: