I wish I knew the answer to your question. Because I am new to this website and new to the group chat thing, I don't know if it is appropriate or not to tell an experience of my own in this thread but it sort of relates to what you have described.
Without getting into all the details, I will just say what I've seen in my cctv after someon has enters the property an/or home.
It's happened during the day and the night. I will see a bright flash of light from under Or behind the FOV of the camera or from outside over the neighbors wall. During the day, the cameras image will turn to black and white then freeze for a short period of time, then they slowly fade back to normal. At night, because of the night vision, the camera picture is already black and whit but still freezes then slowly comes back on.
i have showed this to people who you would think are experts and all have said it was very strange and they've never seen it before but couldn't explain it. One person speculated that someone manipulated the voltage to the camera but the flash of light comes from areas where there is now electric panels, like the neighbors yard.
I have been trying to find an answer for years and no longer use cameras because in my situation they have been easily tricked.
I wonder if ago made EMP device would be capable of doing this.