Before we dive into the process, let's discuss some reasons why you might want to downgrade to Android 11. Perhaps you're not a fan of the new features in Android 12, or maybe you're experiencing bugs or performance issues that weren't present in Android 11. Whatever the reason, downgrading can be a good option.
from the phone. Users are advised to use services like Google Photos or the OnePlus Switch app to secure their files before starting. The Local Update Tool downgrade oneplus 9 to android 11 exclusive