Redmi 12 - screen backlight stops working after locking/unlocking the screen for a few times

[sem1c0lon]

Current Behavior:

If I will press the power button for a few times, ~15 times I'd say, the next attempt to unlock I will see very dark text, icons, because the backlight of the screen stops working. Before I thought that the phone itself didn't woke up, however when this happened to me while I was outside and I could see the screen clock, on the lock screen, because of the bright sun. So this has to do something with the backlight.
Also, sometimes I can let's say scroll on the touchscreen and it will scroll, during this weird state, but sometimes it's completely frozen. After a few minutes of being in this weird state the phone just performs a soft-reboot on it's own.

Describe the bug

While the phone is in this state, I can do adb shell pkill surfaceflinger to trigger a soft reboot and everything is working fine until I trigger the bug again.

If in this state, I do adb logcat, I see tons of errors "04-07 16:55:50.262 1003 1060 E android.hardware.sensors@2.0-service.multihal-mediatek: MMCKJ6a 20200831 inVG mag -0.098201 0.186791 -0.454408 acc -0.129286 0.033265 1.006837 ts 0.020004
04-07 16:55:50.262 1003 1060 E android.hardware.sensors@2.0-service.multihal-mediatek: MMCKJ6a 20180831 norm2_VG(acc,3)= 1 norm2_VG(mag,3)=0 StartErrCount=0 ErrCountFlag = 0"

To Reproduce

Lock/unlock the phone for a few times

Smartphone

• Device: Xiaomi Redmi 12
• Build Flavor: arm64 bgN vndklite
• Version: LineageOS 20 by Andy Yan

Additional context

I tried changing various settings related to display/backlight in Phh treble settings however I get the same result.
On stock the issue is not present.

I tried to trigger this issue and let the logcat running until it soft-rebooted on it's own
log.txt

[phhusson]

Relevant extract

04-07 17:07:22.007 29164 29188 W Watchdog: *** WATCHDOG KILLING SYSTEM PROCESS: Blocked in handler on main thread (main), Blocked in handler on ui thread (android.ui)
04-07 17:07:22.010 29164 29188 W Watchdog: main annotated stack trace:
04-07 17:07:22.010 29164 29188 W Watchdog:     at android.hardware.SystemSensorManager$BaseEventQueue.nativeEnableSensor(Native Method)
04-07 17:07:22.010 29164 29188 W Watchdog:     at android.hardware.SystemSensorManager$BaseEventQueue.enableSensor(SystemSensorManager.java:793)
04-07 17:07:22.010 29164 29188 W Watchdog:     at android.hardware.SystemSensorManager$BaseEventQueue.addSensor(SystemSensorManager.java:709)
04-07 17:07:22.010 29164 29188 W Watchdog:     at android.hardware.SystemSensorManager.registerListenerImpl(SystemSensorManager.java:204)
04-07 17:07:22.011 29164 29188 W Watchdog:     - locked <0x040507fa> (a java.util.HashMap)
04-07 17:07:22.011 29164 29188 W Watchdog:     at android.hardware.SensorManager.registerListener(SensorManager.java:798)
04-07 17:07:22.011 29164 29188 W Watchdog:     at com.android.server.power.FaceDownDetector.updateActiveState(FaceDownDetector.java:206)
04-07 17:07:22.011 29164 29188 W Watchdog:     at com.android.server.power.FaceDownDetector.-$$Nest$mupdateActiveState(Unknown Source:0)
04-07 17:07:22.011 29164 29188 W Watchdog:     at com.android.server.power.FaceDownDetector$ScreenStateReceiver.onReceive(FaceDownDetector.java:468)
04-07 17:07:22.011 29164 29188 W Watchdog:     at android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0$android-app-LoadedApk$ReceiverDispatcher$Args(LoadedApk.java:1790)
04-07 17:07:22.012 29164 29188 W Watchdog:     at android.app.LoadedApk$ReceiverDispatcher$Args$$ExternalSyntheticLambda0.run(Unknown Source:2)
04-07 17:07:22.012 29164 29188 W Watchdog:     at android.os.Handler.handleCallback(Handler.java:942)
04-07 17:07:22.012 29164 29188 W Watchdog:     at android.os.Handler.dispatchMessage(Handler.java:99)
04-07 17:07:22.012 29164 29188 W Watchdog:     at android.os.Looper.loopOnce(Looper.java:201)
04-07 17:07:22.012 29164 29188 W Watchdog:     at android.os.Looper.loop(Looper.java:288)
04-07 17:07:22.012 29164 29188 W Watchdog:     at com.android.server.SystemServer.run(SystemServer.java:965)
04-07 17:07:22.012 29164 29188 W Watchdog:     at com.android.server.SystemServer.main(SystemServer.java:650)
04-07 17:07:22.012 29164 29188 W Watchdog:     at java.lang.reflect.Method.invoke(Native Method)
04-07 17:07:22.012 29164 29188 W Watchdog:     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
04-07 17:07:22.012 29164 29188 W Watchdog:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:914)
04-07 17:07:22.013 29164 29188 W Watchdog: android.ui annotated stack trace:
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.BinderProxy.transactNative(Native Method)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.BinderProxy.transact(BinderProxy.java:584)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.app.IUidObserver$Stub$Proxy.onUidIdle(IUidObserver.java:280)
04-07 17:07:22.013 29164 29188 W Watchdog:     at com.android.server.am.UidObserverController.dispatchUidsChangedForObserver(UidObserverController.java:281)
04-07 17:07:22.013 29164 29188 W Watchdog:     at com.android.server.am.UidObserverController.dispatchUidsChanged(UidObserverController.java:211)
04-07 17:07:22.013 29164 29188 W Watchdog:     at com.android.server.am.UidObserverController$$ExternalSyntheticLambda0.run(Unknown Source:2)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.Handler.handleCallback(Handler.java:942)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.Handler.dispatchMessage(Handler.java:99)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.Looper.loopOnce(Looper.java:201)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.Looper.loop(Looper.java:288)
04-07 17:07:22.013 29164 29188 W Watchdog:     at android.os.HandlerThread.run(HandlerThread.java:67)
04-07 17:07:22.013 29164 29188 W Watchdog:     at com.android.server.ServiceThread.run(ServiceThread.java:44)
04-07 17:07:22.014 29164 29188 W Watchdog:     at com.android.server.UiThread.run(UiThread.java:45)```

[sem1c0lon]

also have found a weird bug, working with the flashlight is awful - e.g. i clicked the flashlight quick tile, and after locked the phone. and it wont unlock ever again. however the flashlight is fine after I reboot / kill surfaceflinger
and it also soft reboots in this state after a few minutes... very weird

[Captain-Starlet]

I noticed one way to bypass Soft Reboot on the same device (Xiaomi Redmi 12 4GB/64GB). I turned off all sensors for the duration of testing using the following algorithm:

• go to "Settings" - "System" - "For Developers" - "Elements in quick settings" and check the box "Sensors disabled";
• in quick settings (in the curtain) adds the “Sensors disabled” button and turns it on.

In total, the phone works without reboots or freezes.

How can you turn off the sensors one by one to identify which one is causing the malfunction?