You said everything was working great, until you changed two things. My suggestions weren’t ideas for things to change, they were ideas for tests, so that you can identify the issue. No issue, then issue, and you had changed two things.
Leave all as was, including sensitivity, since that was not an issue before. Remove flag, issue goes away, its the flag. Issue does not go away, in the absence of flag, it’s not the flag, and you can forget it.
Leave all as was, remove the lights, or turn them off. Issue goes away, it’s the lights. Issue remains, it’s not the lights.
Should be one or the other, because you said it worked fine until you changed those two things. If you changed other things, you didn’t mention them.
Once you know which of the two it is, then you can decide how to address it. If it’s neither, I couldn’t say, unless there was some other change.
Probably the flag, because activity zones don’t work too well. By the way, even if the zoned out flag doesn’t cause recordings, it will be tripping your camera all night, and wasting the batteries, because of how activity zones work.
Flag moves, PIR sensor ‘sees’ it. PIR sensor wakes camera. Camera takes two images, a short while apart. Camera does image comparison in the non zoned out areas. No change between the two, go back to sleep. Any change between the two, continue recording, and upload video. Flag waves, PIR sensor ‘sees’ it. PIR sensor wakes camera …
Point being, it will do this over and over again, even if it never uploads anything, so even if the zones works out well for you with the flag, and it turns out it wasn’t the issue, it’s still not a good idea to have it there, because your batteries will run out quickly. If windy, I could imagine that test being performed hundreds of times per night. If powered, I don’t suppose it matters.