Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wb0/STM32WB09/TRNG/TRNG_DEFKEY3#0x0
TRNG_DEFKEY3 register
Bits 127 to 96 of AES 128-bit Default Key.
https://github.com/modm-io/cmsis-svd-stm32