Xiaomi Mi Max 3

Issues

Backlight flickering (Android 11)

Go to Settings -> Treble Settings -> Misc Settings Scroll to Backlight section, and tick "Use alternate backlight scale" issue

Music does not play via Bluetooth

Instead, it is played through the phone speakers even when connected to a bluetooth device.

No known solution

GPS is slow to start

Workaround: Install GPS Test and reset A-GPS database. Then launch it a couple of times outdoors and let it connect 4+ satellites. That should restore A-GPS to normal function.