Status indicator red, but AC flied flawlessly?

[quirom]

I have flied my MPP for 50+ flights, no problem so far (except 1 time lost RC connection, a few times app disconnected, restart fixed, no big deal). Pretty often that I see the status indicator has red color flashing. I am sure that is not low battery warning. Could it be IMU error? I calibrated IMU once after opening the box. The app never reported any IMU error.
What is exact meaning of that red flashing? I see that quite often.

 

[Thomas B]

Here’s what the full online version of the user manual says.

 

[quirom]

Here’s what the full online version of the user manual says.
View attachment 80089

I knew this, just weird that I have no error.

 

[quirom]

Did some researches, looks like due to NFZ nearby. Explained eveything.