This is not poor. With 2 active sims that is actually quite good. Just think for a minute why the flagships of the top companies almost never get dual sim option (at least in Europe and America). If you need dual sim there are some downs to that.
I got a root. After that, I changed the minimum frequencies of the processor (they are high in the drain, no matter what mode we choose). Chosen by a conservative governor. Removed all Google software. I set the refresh rate to 60 Hz. Disabled AOD. Sim one is 3g, the other is 2g. But I still get the same 5-6 hours. I have a suspicion that the reason for the fast discharge is the radio module.
So I have Zenfone 8 since June and battery life is OK, I can get through a day. Saying that I am a pretty heavy user as I had to charge my pixel 3 twice in a day, while now when my father is using it, battery lasts for 2 days with 4-5h screen on time.
Here is my accubattery estimates. They have gone from 6h 10min to 6h 48m in the last week, so maybe the adaptive battery is affecting this.
I solved mine with another cable, for some reason the PD 30W cable I bought for the phone prevented connection to the Skoda, used an old type C cable it works fine. Android pay started working again randomly, seemingly after raised a case with Google themselves.
I've given up the 120hz, Battery life is fine for me now (on auto) and I'm getting about 6 .5 hours screentime. Disabled Bluetooth and WiFi location scanning and renabled 5G. 90% charging limit.
Mostly happy with the phone although Asus needs to be much more careful software updates.
Hoping and praying
I don't wake up with the phone bricked due to the ramdump issue. Keeping an eye on the Zentalk forum for how Asus deals with this ( may influence me to trade the phone in earlier, don't want a £600 paperweight)
Going to be checking for the Xperia 5iii as I believe it has a bigger battery. Can't see anything else coming out which is compact-ish , high end and Android.