Some users iPhone recently reported a noticeable decrease in smartphone battery life after installing the iOS 18 update, with some people experiencing 20-30% battery drain in just an hour.
Apple made several suggestions. To begin with, you should update the beta version to the latest version of the firmware, if someone has not done this yet. Apple Support states that users can use their iPhones immediately after the update, but some processes continue to run in the background, temporarily affecting battery life and temperature.
These background tasks may cause the device to consume more power for a while after the update. Apple confirmed that battery usage will stabilize within a few days as the system adapts to the new update.