Streamline Capture: What the Android Thermal Throttling chart levels mean

Hi guys,

I'm looking at several data charts captured through Streamline. Among them, regarding the heat of the device, I am carefully looking at the android thermal throttling chart. Basically, the values in this chart are at 8 levels including the error value. But can I get more details on what each level means?
For example, in my game, this level goes up one step at a time for a certain period of time and eventually reaches the Severe level and stays on without falling. What does the Severe level mean in this case? From an optimization point of view, is it acceptable if the Severe level is reached when the app starts? (Of course, it would be best if you didn't reach that level).
This is a very important indicator in the battery consumption issue, so a more detailed explanation would be very helpful.