Once you reach the OxygenOS 11 home screen, prevent the device from immediately downloading newer software versions: Go to > System > System Updates . Tap the Gear icon in the top right corner. Turn off Auto-download over Wi-Fi . Restore Your Backup
Use or the built-in Google backup to save: downgrade oneplus 9 to android 11 exclusive
Download the official Android 11 rollback ZIP files directly from the OnePlus community repository or reliable firmware archives like XDA Developers. Save this file directly to your computer or your phone's storage. Phase 3: The Rollback Procedure Once you reach the OxygenOS 11 home screen,