When you install the app from IPA file, it cannot run on iOS 15 with following error.
"xxx" Needs to Be Updated The developer of this app needs to update it to work with this version of iOS
It's cause of old version of code sign of the app. This error is occurred if you export your IPA on macOS 10.15 (and previous version) and Xcode 12.4 (and previous version).
You have to export IPA with macOS 11 and Xcode 12.5.1.
- This error is not occurred if you install the app from App Store.