I have found this:
The earlier A7 III did not incorporate the "Real-time Tracking AF" technology that Sony first debuted with the A6400 and A9 via a firmware update back in 2019. The A7 III still had tracking autofocusing, called Lock-on AF, but it's not as capable or as high-speed as this current implementation. With Real-time Tracking AF, the A7 IV is better equipped to detect and track a wide variety of different subjects, including people and certain animals, including birds. It's also better able to handle challenging subject-tracking situations better than Lock-on AF could, such as continually tracking a moving person's face and eyes even if the face or eyes are briefly obscured from view (i.e. the subject turns away from the camera) or the leaves the frames. The A7 IV can now maintain focus on the subject and quickly reacquire precision face/eye focus once the subject returns into the frame.
Who knows, maybe a software update will come for your camera as well.
The guy over here takes a lot of time explaining but he does explain how to focus on birds without the need of birds eye autofocus.
