Hi there! It sounds like you're facing compatibility issues with the Tuta app on iOS 15. This can happen when the app version isn't fully optimized for the latest system updates. Based on the information I found, the Tuta app may require iOS 16.0 or later to function properly, which means it might not work well with iOS 154.

Upgrading your device just for app compatibility might not be necessary. Here are a few things you can try:

1. App Update: Check if there's an update available for the Tuta app. Sometimes app developers release updates to fix compatibility issues with new operating systems.

2. Reinstall the App: Uninstall and then reinstall the Tuta app. This can sometimes resolve glitches or compatibility problems.

3. Contact Support: Reach out to Tuta support to see if they can offer any workarounds or if they're planning an update to address this issue5.

Would you like to try any of these steps, or do you have any other questions?