If you have HomePods and worse-than-expected battery life on iPhone, try turning off Settings > General > AirPlay > “Transfer to HomePod.” It’s expensive in power as it’s constantly ranging.
In the screenshot, I turned off the setting during the middle charge. First time I have seen flat battery drain in months.
Another unexpected drain: the Finder device setting “Show this iPhone when on Wi-Fi” causes a large amount of energy usage by lockdownd, via saagar.
Discovered this using his excellent sysdiagnose energy log viewer.