Thank you everyone.
I have tried turning both phones off then on - no change to drain
Mine was purchased in November 2019 and is covered by Applecare until November this year. My understanding is that Apple won’t replace the battery until it drops to less than 80% ( looks like I won’t meet that target by then - what a clever design!)
I have checked several optimisation tips. My issue is that the battery discharges relatively quickly when it is sitting there asleep. So it seems something that consumes power is running in the background but it doesn’t show up in the Battery Usage list.
I do have Bluetooth turned on all the time (paired with my watch). I suppose I could try turning that off for troubleshooting purposes. If it is this then it likely has something to do with recent OS updates.
I turned wifi (cell phone) calling off yesterday evening and the discharge rate still seems to be on the same trajectory this morning.
It’s not the Covid app. Much to my frustration we don’t have a Covid app operating in Australia. The government paid $6 million last year for an app that didn’t work in a practical way on iPhones. No sign of an update that uses the Apple/Android API.