What is the device behavior when operating near the maximum junction temperature? Specifically what is/are the failure mode(s)? Leakage current? Latch-up? Die melt?

[KHepp.1]

Have an application for STM32WB55 which is likely to be occasionally exposed to 125C (max) ambient, but with very low power consumption. What is the behavior at the allowed limit? Do leakage currents increase dramatically (leading to thermal runaway). Is latch-up more likely (not recoverable by watchdog)? Datasheet only provides behavior up to 105C.

[S.Ma]

Well if you go beyond what is in the datasheet normal operating conditions, the longevity and warranty of the chip is void.

The absolute maximum rating typically means the chip will survive probably 1000 hours.

The junction temperature can be simulated/calculated knowing the ambiant, the package Theta Tj thermal resistance, and the chip power dissipation/power. Not specialist. 125C seems industrial grade device requirement.

[S.Ma]

Food for thoughts... here