My first replacement device has started flickering, only five days after getting it - as I knew it probably would.
It’s currently running the latest software available OTA on Optus - 1.28.980.10. As mentioned here there’s a newer version which has the capability of (hopefully) fixing the flickering issue permanently.
I can’t decide on whether to take the phone back again, all they’ll do is eventually replace it. The fact that there’s a dead red pixel in the top of the screen makes me want to take it back… why can’t they just make this stuff work?