Hello Circleof05ths,
Thanks for that info. Yes, since it's across multiple devices, leave feedback.
Apple might make changes in the upcoming iOS updates: Feedback - iPhone - Apple
Your iPhone may heat up and lose battery in long calls too. It will heat up more if you put it on the charger while on the call too. Try saving power in other areas. Check that you are updated, then wait 72 hours for background functions to complete, and test again.
Your iPhone battery is designed to retain 80% max capacity at 500 charge cycles. Meaning, if an issue is found later, the warranty would cover it as mentioned here: https://s.apple.com/dm3l9J0G8w
“A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles when operating under normal conditions. The one-year warranty includes service coverage for a defective battery. If it is out of warranty, Apple offers battery service for a charge.”
Battery percentage and charge cycles are both a direct result of use and charging, please check your settings, as some simple changes can really help extend the life of your battery. This same article should help: https://s.apple.com/dH1R1T4z3w
Follow this for more tips: https://s.apple.com/dH5z9T8n0O
It may also be beneficial to disable Background App Refresh for the apps that you do not normally use. This article talks about Background App refresh: https://s.apple.com/dH8h5u3i4b
Also, check if your model is capable of this, as it greatly reduces the battery life with active listening. Go to Settings > Accessibility > Sound Recognition, then turn off Sound Recognition if it is on. This feature uses a lot of battery that was not consistent with other usage. Please check for Sound Recognition feature. Once turned off, battery usage should go back to expected use.
Lastly, check Settings > Battery > Last 24 hours tab > and check Screen On / Screen Off and the top 6 or 8 apps in that list. Does it look like any apps are running more or using more power than you expect to be used? For example, you checked your Mail for 30 minutes in the last 24 hours, but the app has been running for 8 hours? https://s.apple.com/dw6n7U1EK8
Thanks.