Question:

After doing factory data reset, Bluetooth has been enabled even though I did not activate.

Answer:

After performing a factory data reset, Bluetooth may be automatically enabled due to changes implemented in Android 11. By default, the Bluetooth setting is now set to "On." Additionally, Bluetooth is designed to maintain an active connection to improve user experience when connected to devices like media streaming devices or hearing aids using Audio Streaming for Hearing Aids (Asha) via Bluetooth low energy, even when airplane mode is activated.