I mentioned Terry because he very clearly intentionally made himself big with the idea of using any part of his body to block shots. He did it on a regular basis and was not penalised often enough.
That very obviously was not what Jack did yesterday. If you look at the right video angle you see Jack has his eyes closed and didn’t see the ball, wasn’t making himself big or doing anything unnatural.
Neither situation is difficult to interpret correctly.
If you go back to first principles, handball has to be deliberate and that has to extend to not deliberately keeping your arm out of the way / taking evasive action where you can.
I believe that referee’s should make judgements on that, they make judgements on other rules. The issue is, and long has been, having referees who are competent at making those decisions.
I hate VAR with a passion, but making big decisions (in the box) should be even easier with access to multiple video angles etc.