Hey there RevanMandalore,
Battery life may be less than expected for a short time after updating. This occurs due to it downloading app data, syncing contacts, indexing search results, and completing the digital housekeeping for a new update. We recommend following these battery tips going forward: Batteries - Maximizing Performance
While we recommend monitoring the battery life for the same issue after 72 hours from updating(in conjunction with using our battery tips), we’d like to rule out some other possible causes:
1. A screenshot of what shows within Settings > Battery > Battery Health & Charging.
2. A screenshot of the app/feature that was using the most battery within Settings > Battery > Last 24 Hours > Battery Usage, along with the percentage it used after tapping on ‘Show Battery Usage’.
3. Is it being used within its temperature range? Check for the range near the top here: If your iPhone or iPad gets too hot or too cold
4. Any app updates available? Here are the steps to check: How to manually update apps on your Apple device
5. Which exact iOS 15 version is installed under Settings > General > About?
6. How many hours is the battery lasting from a full charge?
7. If you recently updated, how many days ago was it installed?
Cheers!