GrapheneOS
I don't remember exactly whether it only happened with this version, but the energy consumption of the Pixel 8 Pro is much higher than that of its predecessor, the 7 Pro, with almost identical software and a completely identical system configuration.
P7P: 1 % energy consumption in pure standby with 5G mobile communications after 1:00 h (sometimes 1:30 h)
P8P: 1 % energy consumption in pure standby with 5G mobile communications after 25 min.
In previous versions, the Pixel 8 Pro usually took around 50 minutes in standby before the battery lost 1%.
– The only difference regarding mobile radio: Dual eSIM (both Telefónica) on P8P, one eSIM on P7P.
– The only difference regarding apps: Threema Libre is installed on the P8P and SimpleX Chat is installed on the P7P. However, as SimpleX Chat does not have such an efficient push system, I have not set its notifications to the highest priority. Nevertheless, the battery lasts much longer. So messengers are not the cause.
However, I can see under Settings/Battery/Battery usage (Filter by system) that mobile phone usage on the P8P is 72% (Total: 14 h 18 min.) and on the P7P it is only 57% (Total: 3 days 22 h 17 min.).
A slightly older modem software is installed on the P8P than on the P7P (Provider: Telefónica Germany)
Modem version details:
P7P: eplus_de-52000000018 2023-08-30
P8P: eplus_de-52000000006 2023-08-30
I have also tested Flight mode: then the P8P reaches normal energy consumption like 1% standby in 1 h or more.
BTW: Since day one of using the energy consumption at night with Flight and low-power mode the P8P is 3–4% and with my P7P 2% only.