NvRmTmonZoneId_Core is measured from a sensor within the T30 chip.
NvRmTmonZoneId_Module is taken from an additional temperature sensor which is located in another place on the Apalis module.
The behavior is somewhat more complicated:
As a first measure the system limits the performance whenever the core temperature gets too high:
T_SoC < 60 °C: no limitation
T_Soc = 60 °C to 85 °C: Core frequency limits to 800 MHz
T_SoC > 85 °C: Core frequency decreases in steps down to 500 MHz
The system continues to work properly, but the limited performance can affect the behavior of a device.
If the core temperature rises above 115°C, or the module temperature rises above 95°C, the system does an emergency shutdown.
There are two developer page articles regarding this topic. But I just found, the information is slightly outdated and requires an update from our side: