There was an update , that bricked your drone if you have any sensor issues, with the drone before or you had a light that was out on the drone, that one update could be the issue.
Phantomrain.org
Gear to fly in the Rain. Land on the Water.
I wouldn't do any firmware change unless absolutely necessary. Best to do an IMU calibration any time your flights turn wonky/abnormal..instructions in the FLY app.That usually cures what ails ya.
I had this on my Air 3s until a couple of firmware updates ago Mainly flying into a bright sun, but issues seems to have been fixed and I no longer get the OA alerts mid flight. No birds etc in vicinity when the alert used to come on.